% Encoding: UTF-8
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@article{faucris.123019644,
abstract = {By means of experiments in microgravity conditions, we show that granular systems subjected to sinusoidal vibrations respond either by harmonic or gaslike dynamics, depending on the parameters of the vibration, amplitude and frequency, and the container size, while subharmonic response is unstable, except for extreme material properties and particular initial conditions. The absence of subharmonic response in vibrated granular systems implies that granular dampeners cannot reveal higher-order resonances, which makes them even more attractive for technical applications. Extensive molecular dynamics simulations support our findings.},
author = {Kollmer, Jonathan and Tupy, Martin and Heckel, Michael and Sack, Achim and Pöschel, Thorsten},
doi = {10.1103/PhysRevApplied.3.024007},
faupublication = {yes},
journal = {Physical Review Applied},
peerreviewed = {Yes},
title = {{Absence} of subharmonic response in vibrated granular systems under microgravity conditions},
volume = {3},
year = {2015}
}
@article{faucris.111557204,
abstract = {We study actively rotating granular particles manufactured by rapid prototyping. Such particles, as introduced in Ref. [1], convert vibrational motion into rotational motion via tilted elastic legs in a circular arrangement at the bottom of the particle. We extend the original design of the particles to make them suitable for mass-fabrication via rapid prototyping. The rotational velocity is measured in dependence of the driving frequency and amplitude. We find two different regimes of motion. For small amplitudes the particle performs a slow and stable rotation, while above a certain threshold the particle starts to perform a precission and consequently rotates significantly faster.},
author = {Scholz, Christian and Pöschel, Thorsten},
faupublication = {yes},
journal = {Revista Cubana de Fisica },
pages = {37-38},
peerreviewed = {unknown},
title = {{Actively} rotating granular particles manufactured by rapid prototyping},
url = {http://www.mss.cbi.fau.de/content/uploads/granular{\_}particles{\_}revcubfis{\_}2016.pdf},
volume = {33},
year = {2016}
}
@article{faucris.109888944,
abstract = {We discuss a new optimization strategy, which considerably improves the effectivity of evolutionary algorithms applied to a certain class of optimization problems. The basic principle is to solve first a simpler related problem, which is constructed by introducing additional degrees of freedom to the landscape. Starting from the solution in this simplified landscape we remove stepwise the added degrees of freedom. Our optimization strategy is demonstrated for a sample problem.},
author = {Buchholtz, Volkhard and Pöschel, Thorsten},
doi = {10.1142/S0218127497000546},
faupublication = {no},
journal = {International Journal of Bifurcation and Chaos},
pages = {751-757},
peerreviewed = {Yes},
title = {{Adaptive} evolutionary optimization of team work},
volume = {7},
year = {1997}
}
@article{faucris.308935235,
abstract = {We introduce an innovative instrument designed to investigate fluid-induced fractures under mixed loading conditions, including uniaxial tension and shear stress, in gels and similar soft materials. Equipped with sensors for measuring force, torque, and fluid pressure, the device is tailored for compatibility with x-ray tomography scanners, enabling non-invasive 3D analysis of crack geometries. To showcase its capabilities, we conducted a study examining crack-front segmentation in a hydrogel subjected to air pressure and a combination of tension and shear stress.},
author = {Santarossa, Angel and Ortellado, Laureano and Sack, Achim and Gómez, Leopoldo R. and Pöschel, Thorsten},
doi = {10.1063/5.0145709},
faupublication = {yes},
journal = {Review of Scientific Instruments},
note = {CRIS-Team Scopus Importer:2023-08-11},
peerreviewed = {unknown},
title = {{A} device for studying fluid-induced cracks under mixed-mode loading conditions using x-ray tomography},
volume = {94},
year = {2023}
}
@inproceedings{faucris.119875624,
abstract = {We develop an analytical theory of adhesive interaction of viscoelastic spheres in quasistatic approximation. Deformations and deformation rates are assumed to be small, which allows for the application of the Hertz contact theory, modified to account for viscoelastic forces. The adhesion interactions are described by the Johnson, Kendall, and Roberts theory. Using the quasistatic approximation we derive the total force between the bodies which is not sufficiently described by the superposition of elastic, viscous and adhesive contributions, but instead an additional cross-term appears, which depends on the elastic, viscous and adhesive parameters of the material. Using the derived theory we estimate the contribution of adhesive forces to the normal coefficient of restitution and derive a criterion for the validity of the viscoelastic collision model. © 2005 Taylor & Francis Group.},
author = {Brilliantov, Nikolai V. and Pöschel, Thorsten},
booktitle = {5th International Conference on the Micromechanics of Granular Media: Powders and Grains 2005},
faupublication = {no},
isbn = {9780415383479},
pages = {505-508},
title = {{Adhesive} interactions of viscoelastic spheres},
url = {https://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=84857585813&origin=inward},
venue = {Stuttgart},
volume = {1},
year = {2005}
}
@article{faucris.240533439,
abstract = {A vast majority of widely accepted granular segregation mechanisms are attributed to dynamic phenomena such as percolation, kinetic sieving, convection-induced segregation, condensation, inertia and granular temperature gradients. We distinguish the ballistics of the particles from such dynamic and material properties and show that the former is a dominant mechanism in the segregation of particles sedimented in a container. We first perform granular sedimentation experiments with glass beads in water that exhibit size-segregation of bidisperse grains. We then show through simulations using a simple, first-order model that the ballistics of the particles alone is sufficient to qualitatively predict this segregation.},
author = {Nair, Prapanch and Torres Cisneros, Luis Armando and Windows-Yule, Christopher Robert Kit and Agrawal, Nikhil and Roy, Shantanu and Pöschel, Thorsten},
doi = {10.1016/j.powtec.2020.06.036},
faupublication = {yes},
journal = {Powder Technology},
keywords = {Bidisperse system; Granular packing; Granular segregation; Overdamped phenomena},
note = {CRIS-Team Scopus Importer:2020-07-17},
pages = {357-361},
peerreviewed = {Yes},
title = {{A} first-order segregation phenomenon in fluid-immersed granular systems},
volume = {373},
year = {2020}
}
@misc{faucris.320111108,
author = {Pöschel, Thorsten and Engel, Michael},
doi = {10.25593/open-fau-455},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Annual} {Report} 2022 of the {Institute} for {Multiscale} {Simulation}},
year = {2023}
}
@article{faucris.106891444,
abstract = {The investigation of regular and irregular patterns in nonlinear oscillators is an outstanding problem in physics and in all natural sciences. In general, regularity is understood as tantamount to periodicity. However, there is now a flurry of works proving the existence of "antiperiodicity", an unfamiliar type of regularity. Here we report the experimental observation and numerical corroboration of antiperiodic oscillations. In contrast to the isolated solutions presently known, we report infinite hierarchies of antiperiodic waveforms that can be tuned continuously and that form wide spiral-shaped stability phases in the control parameter plane. The waveform complexity increases towards the focal point common to all spirals, a key hub interconnecting them all.},
author = {Freire, J. G. and Cabeza, C. and Marti, A. C. and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1038/srep01958},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Antiperiodic} oscillations},
volume = {3},
year = {2013}
}
@article{faucris.120048324,
abstract = {A numerical study that aims to analyze the thermal mechanisms of unsteady, supersonic granular flow by means of hydrodynamic simulations of the Navier-Stokes granular equation is reported in this paper. For this purpose, a paradigmatic problem in granular dynamics such as the Faraday instability is selected. Two different approaches for the Navier-Stokes transport coefficients for granular materials are considered, namely the traditional Jenkins-Richman theory for moderately dense quasi-elastic grains and the improved Garzó-Dufty-Lutsko theory for arbitrary inelasticity, which we also present here. Both the solutions are compared with event-driven simulations of the same system under the same conditions, by analyzing the density, temperature and velocity field. Important differences are found between the two approaches, leading to interesting implications. In particular, the heat transfer mechanism coupled to the density gradient, which is a distinctive feature of inelastic granular gases, is responsible for a major discrepancy in the temperature field and hence in the diffusion mechanisms. © IOP Publishing and Deutsche Physikalische Gesellschaft.},
author = {Garzó, Vicente and Almazan Torres, Lidia and Carrillo, José A. and Salueña, Clara and Pöschel, Thorsten},
doi = {10.1088/1367-2630/15/4/043044},
faupublication = {yes},
journal = {New Journal of Physics},
peerreviewed = {Yes},
title = {{A} numerical study of the {Navier}-{Stokes} transport coefficients for two-dimensional granular hydrodynamics},
volume = {15},
year = {2013}
}
@inproceedings{faucris.119278764,
abstract = {We present three heuristics including the usage of domain specific knowledge to improve a general purpose algorithm for the 3D approximate point set match problem and its application to the task of finding 3D motifs (like surface patterns or binding sites) in proteins. The domain specific knowledge and further heuristics are used, under certain conditions, to reduce the run time for the search and to adapt the number of reported matches to the expectations of the user. Compared to the general purpose algorithm, the new version is twice as fast, and can be further improved especially for small tolerances in the matches by means of analyzing the distance distributions of the atoms.},
author = {Formella, Arno and Pöschel, Thorsten and Sanchez Chao, Castor},
booktitle = {14th Portuguese Conference on Artificial Intelligence},
date = {2009-10-12/2009-10-15},
faupublication = {yes},
pages = {101 - 112},
peerreviewed = {unknown},
title = {{Approximate} {3D} motif search in proteins with domain specific knowledge. {New} {Trends} in {Artificial} {Intelligence}},
venue = {Aveiro},
year = {2009}
}
@article{faucris.109802924,
abstract = {A recent study claimed that heavy use of equations impedes communication among biologists, as measured by the ability to attract citations from peers. It was suggested that to increase the probability of being cited one should reduce the density of equations in papers, that equations should be moved to appendices, and that math training among biologists should be improved. Here, we report a detailed study of the citation habits among physicists, a community that has traditionally strong training and dependence on mathematical formulations. Is it possible to correlate statistical citation patterns and fear of mathematics in a community whose work strongly depends on equations? By performing a systematic analysis of the citation counts of papers published in one of the leading journals in physics covering all its disciplines, we find striking similarities with distribution of citations recorded in biological sciences. However, based on the standard deviations in citation data of both communities, biologists and physicists, we argue that trends in statistical indicators are not reliable to unambiguously blame mathematics for the existence or lack of citations. We digress briefly about other statistical trends that apparently would also enhance citation success.},
author = {Kollmer, Jonathan and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1088/1367-2630/17/1/013036},
faupublication = {yes},
journal = {New Journal of Physics},
keywords = {citation strategies; science communication; social physics},
peerreviewed = {Yes},
title = {{Are} physicists afraid of mathematics?},
volume = {17},
year = {2015}
}
@article{faucris.258182732,
abstract = {Granular systems are of a discrete nature. Nevertheless, it can be advantageous to describe their dynamics by means of continuum mechanical methods. The numerical solution of the corresponding hydrodynamic equations is, however, difficult. Therefore, previous numerical simulations are typically geared towards highly specific systems and frequently restricted to two dimensions or mild driving conditions. Here, we present the first robust general simulation scheme for granular hydrodynamics in three dimensions which is not bound to the above limitations. The performance of the simulation scheme is demonstrated by means of three applications which have been proven as notoriously difficult for numerical hydrodynamic description. Although, by construction, our numerical method covers grain-inertia flows, the presented examples demonstrate that it produces reliable results even in the jammed or high density limit.},
author = {Shakeri, Ali and Schiochet Nasato, Daniel and Müller, Patric and Torres Menendez, Harol and Pöschel, Thorsten},
doi = {10.1017/jfm.2021.291},
faupublication = {yes},
journal = {Journal of Fluid Mechanics},
keywords = {granular media},
note = {CRIS-Team Scopus Importer:2021-05-14},
peerreviewed = {Yes},
title = {{A} robust numerical method for granular hydrodynamics in three dimensions},
volume = {917},
year = {2021}
}
@article{faucris.109896644,
abstract = {We present a simple model for the friction of two solid bodies moving against each other. In a self-consistent way we can obtain the dependence of the macroscopic friction force as a function of the driving velocity, the normal force and the ruggedness of the surfaces in contact. Our results are discussed in the context of friction laws used in earthquake models. © 1993.},
author = {Pöschel, Thorsten and Herrmann, Hans J.},
doi = {10.1016/0378-4371(93)90233-T},
faupublication = {no},
journal = {Physica A-Statistical Mechanics and Its Applications},
pages = {441-448},
peerreviewed = {Yes},
title = {{A} simple geometrical model for solid friction},
volume = {198},
year = {1993}
}
@article{faucris.109900384,
abstract = {The detailed mechanism of the formation of net and branching leaf structures is not known yet. Several mathematical modelling attempts to generate those structures have been made previously, based on biochemical or purely mathematical assumptions. Here, we present a simple model, based on plausible biophysical suppositions, which is able to reproduce the formation of a ramified structure grown out of a single activated cell. © 1994.},
author = {Pöschel, Thorsten and Malchow, H.},
doi = {10.1016/0960-0779(94)90004-3},
faupublication = {no},
journal = {Chaos Solitons & Fractals},
pages = {1883-1888},
peerreviewed = {Yes},
title = {{A} simple model for the growth of ramified leaf structures},
volume = {4},
year = {1994}
}
@article{faucris.122887864,
abstract = {A two-dimensional cellular automaton is introduced to model the flow and jamming of vehicular traffic in cities. Each site of the automaton represents a crossing where a finite number of cars can wait approaching the crossing from each of the four directions. The flow of cars obeys realistic traffic rules. We investigate the dependence of the average velocity of cars on the global traffic density. At a critical threshold for the density the average velocity reduces drastically caused by jamming. For the low-density regime we provide analytical results which agree with the numerical results. © 1995.},
author = {Freund, Jan A. and Pöschel, Thorsten},
doi = {10.1016/0378-4371(95)00170-C},
faupublication = {no},
journal = {Physica A-Statistical Mechanics and Its Applications},
pages = {95-113},
peerreviewed = {Yes},
title = {{A} statistical approach to vehicular traffic},
volume = {219},
year = {1995}
}
@article{faucris.123382644,
abstract = {We study the packing of fine glass powders of mean particle diameter in the range (4-52)μm both experimentally and by numerical DEM simulations. We obtain quantitative agreement between the experimental and numerical results, if both types of attractive forces of particle interaction, adhesion and non-bonded van der Waals forces are taken into account. Our results suggest that considering only viscoelastic and adhesive forces in DEM simulations may lead to incorrect numerical predictions of the behavior of fine powders. Based on the results from simulations and experiments, we propose a mathematical expression to estimate the packing fraction of fine polydisperse powders as a function of the average particle size.},
author = {Ribeiro Parteli, Eric Josef and Schmidt, Jochen and Blümel, Christina and Wirth, Karl-Ernst and Peukert, Wolfgang and Pöschel, Thorsten},
doi = {10.1038/srep06227},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Attractive} particle interaction forces and packing density of fine glass powders},
volume = {4},
year = {2014}
}
@article{faucris.106912564,
abstract = {Large-scale computer simulations are presented to investigate the avalanche statistics of sandpiles using molecular dynamics. We show that different methods of measurement lead to contradictory conclusions, presumably due to avalanches not reaching the end of the experimental table.},
author = {Buchholtz, Volkhard and Pöschel, Thorsten},
doi = {10.1007/BF02174136},
faupublication = {no},
journal = {Journal of Statistical Physics},
keywords = {Granular material; Self-organized criticality},
pages = {1373-1378},
peerreviewed = {Yes},
title = {{Avalanche} statistics of sand heaps},
volume = {84},
year = {1996}
}
@article{faucris.119476324,
abstract = {
We show that the orientation and morphology of bedforms occurring on top of Pluto’s smooth ice coats are consistent with an aeolian origin under conditions of unidirectional flow. From scaling relations for dune size as a function of attributes of atmosphere and sediments, we find that the average diameter of the granular particles constituting such bedforms — assuming an aeolian origin — lies within the range 600 μm< d < 750 μm. Our findings show that, owing to the effect of hysteresis in the minimal threshold wind velocity for saltation, dune migration on Pluto can occur under wind speeds that are common to Earth and Mars.
},
author = {Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1051/epjconf/201714014010},
faupublication = {yes},
journal = {EPJ Web of Conferences},
peerreviewed = {unknown},
title = {{Barchan} dunes on {Pluto}?},
volume = {140},
year = {2017}
}
@incollection{faucris.218986067,
abstract = {Matter appears on our planet, in the solar system and in the rest of Universe in rather different forms.},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3{\_}1},
faupublication = {yes},
isbn = {978-3-030-05734-3},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {1-17},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Basic} physics of gases and plasmas},
volume = {953},
year = {2019}
}
@article{faucris.120054484,
abstract = {We investigate the motion of a hard cylinder rolling down a soft inclined plane. The cylinder is subjected to a viscous drag force and stochastic fluctuations due to the surrounding medium. In a wide range of parameters we observe bistability of the rolling velocity. In dependence on the parameters, increasing noise level may lead to increasing or decreasing average velocity of the cylinder. The approximative analytical theory agrees with numerical results.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai V. and Zaikin, A.},
doi = {10.1209/epl/i2004-10350-y},
faupublication = {no},
journal = {EPL - Europhysics Letters},
pages = {371-377},
peerreviewed = {Yes},
title = {{Bistability} and noise-enhanced velocity of rolling motion},
volume = {69},
year = {2005}
}
@incollection{faucris.286192202,
abstract = {We consider the application of the Boltzmann equation to aggregation kinetics, where the transport mechanism is the ballistic motion of particles. This refers to molecular gases, granular gases, and, hypothetically, dark matter. Two aggregation models are analyzed—random and impact energy-dependent aggregation. The latter is associated with different interparticle forces responsible for agglomeration. We start from the Boltzmann equation governing the evolution of the mass–velocity distribution functions of different species—the agglomerates of different sizes and derive generalized Smoluchowski equations. These describe the time dependence of the agglomerates densities and their mean kinetic energy (partial temperatures). We obtain exact solutions to these equations for simplified cases and develop a scaling theory for the asymptotic behavior of the system. We explore numerically, the agglomeration kinetics and observe a very rich behavior of the system. We reveal new surprising regimes and construct the according kinetic phase diagram. The scaling theory is in excellent agreement with the simulation results.},
author = {Brilliantov, Nikolai V. and Osinsky, Alexander I. and Pöschel, Thorsten},
booktitle = {Nonequilibrium Thermodynamics and Fluctuation Kinetics},
doi = {10.1007/978-3-031-04458-8{\_}10},
editor = {Léon Brenig, Nikolai Brilliantov, Mustapha Tlidi},
faupublication = {yes},
isbn = {978-3-031-04458-8},
note = {CRIS-Team Scopus Importer:2022-12-02},
pages = {191-216},
peerreviewed = {unknown},
publisher = {Springer Science and Business Media Deutschland GmbH},
series = {Fundamental Theories of Physics},
title = {{Boltzmann} {Equation} in {Aggregation} {Kinetics}},
volume = {208},
year = {2022}
}
@article{faucris.109900604,
abstract = {The velocity distribution of a granular gas is analyzed in terms of the Sonine polynomials expansion. We derive an analytical expression for the third Sonine coefficient a. In contrast to frequently used assumptions this coefficient is of the same order of magnitude as the second Sonine coefficient a. For small inelasticity the theoretical result is in good agreement with numerical simulations. The next-order Sonine coefficients a, and a are determined numerically. While these coefficients are negligible for small dissipation, their magnitude grows rapidly with increasing inelasticity for 0 < ε ≲ 0.6. We conclude that this behavior of the Sonine coefficients manifests the breakdown of the Sonine polynomial expansion caused by the increasing impact of the overpopulated high-energy tail of the distribution function. © EDP Sciences.},
author = {Brilliantov, Nikolai V. and Pöschel, Thorsten},
doi = {10.1209/epl/i2005-10555-6},
faupublication = {no},
journal = {EPL - Europhysics Letters},
pages = {424-430},
peerreviewed = {Yes},
title = {{Breakdown} of the {Sonine} expansion for the velocity distribution of granular gases},
volume = {74},
year = {2006}
}
@article{faucris.258191566,
abstract = {We show that the permeability of periodic simply connected porous media can be reliably predicted from the Minkowski tensors (MTs) describing the pore microstructure geometry. To this end, we consider a large number of two-dimensional simulations of flow through periodic unit cells containing complex-shaped obstacles. The prediction is achieved by training a deep neural network using the simulation data with the MT elements as attributes. The obtained predictions allow for the conclusion that MTs of the pore microstructure contain sufficient information to characterize the permeability, although the functional relation between the MTs and the permeability could be complex to determine.},
author = {Nair, Prapanch and Mühlbauer, Sebastian and Roy, Shantanu and Pöschel, Thorsten},
doi = {10.1063/5.0045701},
faupublication = {yes},
journal = {Physics of Fluids},
note = {CRIS-Team WoS Importer:2021-05-14},
peerreviewed = {Yes},
title = {{Can} {Minkowski} tensors of a simply connected porous microstructure characterize its permeability?},
volume = {33},
year = {2021}
}
@article{faucris.120500204,
abstract = {The coefficient of restitution may be determined from the sound signal emitted by a sphere bouncing repeatedly off the ground. Although there is a large number of publications exploiting this method, so far, there is no quantitative discussion of the error related to this type of measurement. Analyzing the main error sources, we find that even tiny deviations of the shape from the perfect sphere may lead to substantial errors that dominate the overall error of the measurement. Therefore, we come to the conclusion that the well-established method to measure the coefficient of restitution through the emitted sound is applicable only for the case of nearly perfect spheres. For larger falling height, air drag may lead to considerable error, too.
},
author = {Heckel, Michael and Glielmo, Aldo and Gunkelmann, Nina and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.93.032901},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Can} we obtain the coefficient of restitution from the sound of a bouncing ball?},
url = {http://link.aps.org/doi/10.1103/PhysRevE.93.032901},
volume = {93},
year = {2016}
}
@article{faucris.226865218,
abstract = {The rate of melting of a solid and the rate of deformation of the resulting melt due to capillary forces are comparable in additive manufacturing applications. This dynamic structural change of a melting solid is extremely challenging to study experimentally. Using meshless numerical simulations we show the influence of the flow of the melt on the heat transfer and resulting phase change. We introduce an accurate and robust Incompressible Smoothed Particle Hydrodynamics (ISPH) method to simulate melting of solids and the ensuing fluid-solid interaction. We present validations for the heat transfer across the free surface and the melting interface evolution, separately. We then present two applications for this coupled multiphysics simulation method — the study of rounding of an arbitrarily shaped particle during melting and the non-linear structural evolution of three spheres undergoing agglomeration. In both the studies we use realistic transport and thermal properties for the materials so as to demonstrate readiness of the method for solving engineering problems in additive manufacturing.},
author = {Blank, Michael and Nair, Prapanch and Pöschel, Thorsten},
doi = {10.1016/j.ijheatmasstransfer.2018.11.154},
faupublication = {yes},
journal = {International Journal of Heat and Mass Transfer},
keywords = {Additive manufacturing; Incompressible Smoothed Particle Hydrodynamics; Latent heat; Melting dynamics; Phase change},
note = {CRIS-Team Scopus Importer:2019-09-20},
pages = {1232-1246},
peerreviewed = {Yes},
title = {{Capillary} viscous flow and melting dynamics: {Coupled} simulations for additive manufacturing applications},
volume = {131},
year = {2019}
}
@article{faucris.109106844,
abstract = {This paper reports a detailed numerical investigation of the geometrical and structural properties of three-dimensional heaps of particles. Our goal is the characterization of very large heaps produced by ballistic deposition from extended circular dropping areas. First, we provide an in-depth study of the formation of monodisperse heaps of particles. We find very large heaps to contain three new geometrical characteristics: they may display two external angles of repose, one internal angle of repose, and four distinct packing fraction (density) regions. Such features are found to be directly connected with the size of the dropping zone. We derive a differential equation describing the boundary of an unexpected triangular packing fraction zone formed under the dropping area.We investigate the impact that noise during the deposition has on the final heap structure. In addition, we perform two complementary experiments designed to test the robustness of the novel features found. The first experiment considers changes due to polydispersity. The second checks what happens when letting the extended dropping zone to become a point-like source of particles, the more common type of source.},
author = {Gallas, Jason and Pöschel, Thorsten and Topic, Nikola},
doi = {10.1080/14786435.2013.797618},
faupublication = {yes},
journal = {Philosophical Magazine},
pages = {4090-4107},
peerreviewed = {unknown},
title = {{Characteristics} of large threedimensional heaps of particles produced by ballistic deposition from extended sources},
volume = {93},
year = {2013}
}
@article{faucris.114385524,
abstract = {We report a numerical characterization of the stability of semiconductor lasers with delayed feedback under the simultaneous variation of the delay time \textit{τ }and the pump current P. Changes in the number of External Cavity Modes are studied as a function of the delay time while the Regular Pulse Package regime is characterized as a function of the pump current. In addition, we describe some remarkable structures observed in the \textit{τ ×P }control plane, delimiting where these and other complex regimes of laser operation exist.},
author = {Gallas, Jason A. and Junges, Leandro and Pöschel, Thorsten},
doi = {10.1140/epjd/e2013-40124-4},
faupublication = {yes},
journal = {European Physical Journal D},
pages = {149--158},
peerreviewed = {Yes},
title = {{Characterization} of the stability of semiconductor lasers with delayed feedback according to the {Lang}-{Kobayashi} model},
volume = {67},
year = {2013}
}
@article{faucris.109901704,
abstract = {Granular ratchets are well-known devices that when driven vertically produce a counterintuitive horizontal transport of particles. Here we report the experimental observation of a complementary effect: the striking ability of circular ratchets to convert their vertical vibration into their own rotation. The average revolution speed shows a maximum value for an optimal tooth height. With no special effort the rotation speed could be maintained steady during several hours. Unexpected random arrests and reversals of the velocity were also observed abundantly. © 2012 American Physical Society.},
author = {Heckel, Michael and Müller, Patric and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1103/PhysRevE.86.061310},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Circular} ratchets as transducers of vertical vibrations into rotations},
volume = {86},
year = {2012}
}
@article{faucris.109905884,
abstract = {As the kinetic equations become invalid, the constitutive relations (CRs), necessary for the closure of hydrodynamics, are not derivable from first-principles anymore. An ensemble of monodisperse, nearly elastic hard spheres in such conditions that the standard Navier-Stokes granular hydrodynamics (NSGH) breaks down becuase of large densities, not large inelasticity. This paper aims to check whether a variant of NSGH can still be used in an extreme case whether a variant of NSGH can still be used in an extreme case when the packing fraction is close to the maximum possible value, corresponding to hexagonal packing of spheres.},
author = {Meerson, Baruch and Pöschel, Thorsten and Bromberg, Yaron},
doi = {10.1103/PhysRevLett.91.024301},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Close}-packed floating clusters: {Granular} hydrodynamics beyond the freezing point?},
url = {http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.91.024301},
volume = {91},
year = {2003}
}
@article{faucris.119643744,
abstract = {Dense granular clusters often behave like macro-particles. We address this interesting phenomenon in a model system of inelastically colliding hard disks inside a circular box, driven by a thermal wall at zero gravity. Molecular dynamics simulations show a close-packed cluster of almost circular shape, weakly fluctuating in space and isolated from the driving wall by a low-density gas. The density profile of the system agrees very well with the azimuthally symmetric solution of granular hydrostatic equations employing constitutive relations by Grossman et al., whereas the widely used Enskog-type constitutive relations show poor accuracy. We find that fluctuations of the center of mass of the system are Gaussian. This suggests an effective Langevin description in terms of a macro-particle, confined by a harmonic potential and driven by delta-correlated noise. Surprisingly, the fluctuations persist when increasing the number of particles in the system. © 2007 Springer-Verlag.},
author = {Meerson, Baruch and Díez-Minguito, Manuel and Schwager, Thomas and Pöschel, Thorsten},
doi = {10.1007/s10035-007-0055-1},
faupublication = {no},
journal = {Granular Matter},
keywords = {Granular cluster; Granular hydrodynamics; Strong fluctuations},
pages = {21-27},
peerreviewed = {Yes},
title = {{Close}-packed granular clusters: {Hydrostatics} and persistent {Gaussian} fluctuations},
volume = {10},
year = {2007}
}
@article{faucris.109906764,
abstract = {We investigate the cooling rate of a gas of inelastically interacting particles. When we assume velocity-dependent coefficients of restitution the material cools down slower than with constant restitution. This behavior might have a large influence to clustering and structure formation processes.},
author = {Schwager, Thomas and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.57.650},
faupublication = {no},
journal = {Physical Review E},
pages = {650-654},
peerreviewed = {Yes},
title = {{Coefficient} of normal restitution of viscous particles and cooling rate of granular gases},
volume = {57},
year = {1998}
}
@article{faucris.119186804,
abstract = {With the assumption of a linear-dashpot interaction force, the coefficient of restitution, ε (k, γ), can be computed as a function of the elastic and dissipative material constants, k and γ by integrating Newton's equation of motion for an isolated pair of colliding particles. If we require further that the particles interact exclusively repulsive, which is a common assumption in granular systems, we obtain an expression ε (k, γ) which differs even qualitatively from the known result ε (k, γ). The expression ε (k, γ) allows to relate Molecular Dynamics simulations to event-driven Molecular Dynamics for a widely used collision model. © 2007 Springer-Verlag.},
author = {Schwager, Thomas and Pöschel, Thorsten},
doi = {10.1007/s10035-007-0065-z},
faupublication = {no},
journal = {Granular Matter},
keywords = {Coefficient of restitution; Particle collisions},
pages = {465-469},
peerreviewed = {Yes},
title = {{Coefficient} of restitution and linear-dashpot model revisited},
volume = {9},
year = {2007}
}
@article{faucris.109906984,
abstract = {The coefficient of restitution of a spherical particle in contact with a flat plate is investigated as a function of the impact velocity. As an experimental observation we notice nontrivial (non-Gaussian) fluctuations of the measured values. For a fixed impact velocity, the probability density of the coefficient of restitution, p, is formed by two exponential functions (one increasing, one decreasing) of different slope. This behavior may be explained by a certain roughness of the particle which leads to energy transfer between the linear and rotational degrees of freedom. © 2011 American Physical Society.},
author = {Montaine, Marina and Heckel, Michael and Kruelle, Christof and Schwager, Thomas and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.84.041306},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Coefficient} of restitution as a fluctuating quantity},
volume = {84},
year = {2011}
}
@article{faucris.122894684,
abstract = {The coefficient of normal restitution of colliding viscoelastic spheres is computed as a function of the material properties and the impact velocity. From simple arguments it becomes clear that, in a collision of purely repulsively interacting particles, the particles lose contact slightly before the distance of the centers of the spheres reaches the sum of the radii, that is, the particles recover their shape only after they lose contact with their collision partner. This effect was neglected in earlier calculations, which leads erroneously to attractive forces and thus to an underestimation of the coefficient of restitution. As a result we find a different dependence of the coefficient of restitution on the impact rate. © 2008 The American Physical Society.},
author = {Schwager, Thomas and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.78.051304},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Coefficient} of restitution for viscoelastic spheres: {The} effect of delayed recovery},
volume = {78},
year = {2008}
}
@article{faucris.109805124,
abstract = {We consider the motion of an aspherical inelastic particle of dumbbell type bouncing repeatedly on a horizontal flat surface. The coefficient of restitution of such a particle depends not only on material properties and impact velocity but also on the angular orientation at the instant of the collision whose variance is considerable, even for small eccentricity. Assuming random angular orientation of the particle at the instant of contact we characterize the measured coefficient of restitution as a fluctuating quantity and obtain a wide probability density function including a finite probability for negative values of the coefficient of restitution. This may be understood from the partial exchange of translational and rotational kinetic energy.},
author = {Glielmo, Aldo and Gunkelmann, Nina and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.90.052204},
faupublication = {yes},
journal = {Physical Review E - Statistical, Nonlinear, and Soft Matter Physics},
peerreviewed = {Yes},
title = {{Coefficient} of restitution of aspherical particles},
volume = {90},
year = {2014}
}
@article{faucris.109909184,
abstract = {We perform a dimension analysis for colliding viscoelastic spheres to show that the coefficient of normal restitution ε depends on the impact velocity g as ε=1-γg+γg+ ⋯, in accordance with recent findings. We develop a simple theory to find explicit expressions for coefficients γ and γ. Using these and few next expansion coefficients for ε(g) we construct a Padé approximation for this function which may be used for a wide range of impact velocities where the concept of the viscoelastic collision is valid. The obtained expression reproduces quite accurately the existing experimental dependence ε(g) for ice particles.},
author = {Ramirez, Rosa and Pöschel, Thorsten and Brilliantov, Nikolai and Schwager, Thomas},
doi = {10.1103/PhysRevE.60.4465},
faupublication = {no},
journal = {Physical Review E},
pages = {4465-4472},
peerreviewed = {Yes},
title = {{Coefficient} of restitution of colliding viscoelastic spheres},
volume = {60},
year = {1999}
}
@article{faucris.109910724,
abstract = {The linear dashpot model for the inelastic normal force between colliding spheres leads to a constant coefficient of normal restitution, εn =const, which makes this model very popular for the investigation of dilute and moderately dense granular systems. For two frequently used models for the tangential interaction force we determine the coefficient of tangential restitution, εt, both analytically and by numerical integration of Newton's equation. Although εn =const for the linear-dashpot model, we obtain pronounced and characteristic dependences of the tangential coefficient on the impact velocity, εt = εt (g). The results may be used for event-driven simulations of granular systems of frictional particles. © 2008 The American Physical Society.},
author = {Becker, Volker and Schwager, Thomas and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.77.011304},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Coefficient} of tangential restitution for the linear dashpot model},
volume = {77},
year = {2008}
}
@article{faucris.122956724,
abstract = {The collision of frictional granular particles may be described by an interaction force whose normal component is that of viscoelastic spheres while the tangential part is described by the model by Cundall and Strack (G´ eotechnique 29, 47 (1979)) being the most popular tangential collision model in Molecular Dynamics simulations. Albeit being a rather complicatedmodel, governed by 5 phenomenological parameters and 2 independent initial conditions, we find that it is described by 3 independent parameters only. Surprisingly, in a wide range of parameters the corresponding coefficient of tangential restitution, εt, is well described by the simple Coulomb law with a cut-off at εt = 0. A more complex behavior of the coefficient of restitution as a function on the normal and tangential components of the impact velocity, gn and gt, including negative values of εt, is found only for very small ratio gt/gn. For the analysis presented here we neglect dissipation of the interaction in normal direction.},
author = {Schwager, Thomas and Becker, Volker and Pöschel, Thorsten},
doi = {10.1140/epje/i2007-10356-3},
faupublication = {yes},
journal = {European Physical Journal E},
pages = {107--114},
peerreviewed = {Yes},
title = {{Coefficient} of tangential restitution for viscoelastic spheres},
volume = {27},
year = {2008}
}
@inproceedings{faucris.122137884,
abstract = {We investigate the collective dissipative behavior of a model granular material (steel beads) when subjected to vibration. To this end, we study the attenuation of the amplitude of an oscillating leaf spring whose free end carries a rectangular box partly filled with granulate. To eliminate the perturbing influence of gravity, the experiment was performed under conditions of microgravity during parabolic flights. Different regimes of excitation could be distinguished, namely, a gas-like state of disordered particle motion and a state where the particles slosh back and forth between the container walls in a collective way, referred to as collect-and-collide regime. For the latter regime, we provide an expression for the container size leading to maximal dissipation of energy, that also marks the transition to the gas like regime. Also for systems driven at fixed amplitude and frequency, we find both the gas regime and the collect-and-collide regime resulting in similar dissipative behavior as in the case of the attenuating vibration. © 2013 AIP Publishing LL},
author = {Kollmer, Jonathan and Sack, Achim and Heckel, Michael and Zimber, Fabian and Müller, Patric and Bannerman, Marcus and Pöschel, Thorsten},
booktitle = {7th International Conference on Micromechanics of Granular Media: Powders and Grains 2013},
doi = {10.1063/1.4812055},
faupublication = {yes},
isbn = {9780735411661},
keywords = {damping; Granular material},
pages = {811-814},
peerreviewed = {Yes},
title = {{Collective} granular dynamics in a shaken container at low gravity conditions},
venue = {Sydney, NSW},
volume = {1542},
year = {2013}
}
@article{faucris.269646845,
abstract = {A two-dimensional granular packing under horizontally circular shaking exhibits various collective motion
modes where nonuniform density distribution and correlated dynamics are present. For intermediate packing
density and oscillation amplitude, a condensed phase travels around the container’s side wall in the clockwise
direction, while the oscillation itself is set anticlockwise. Further increasing the packing density towards that of
hexagonal packing, the whole packing rotates collectively in the clockwise direction. The core of the packing
rotates as a solid and is separated from the boundary by a fluid-like layer. Both motion modes are associated
with the asymmetric motion of particles close to the side wall in one oscillation cycle, where the dependence of
particle velocity on the local density plays a key role.
Besides its importance for science and engineering, the process of drop formation from a homogeneous jet or at a nozzle is of great aesthetic appeal. In this paper, we introduce a low-cost setup for classroom use to produce quasi-high-speed recordings with high temporal and spatial resolution of the formation of drops at a nozzle. The visualization of the process can be used for quantitative analysis of the underlying physical phenomena.
},
author = {Sack, Achim and Pöschel, Thorsten},
doi = {10.1119/1.4979657},
faupublication = {yes},
journal = {American Journal of Physics},
peerreviewed = {Yes},
title = {{Dripping} faucet in extreme spatial and temporal resolution},
volume = {85},
year = {2017}
}
@article{faucris.107138064,
abstract = {Ratchets are simple mechanical devices which combine spatial asymmetry and nonequilibrium to produce counterintuitive transport of particles. The operation and properties of linear ratchets have already been extensively explored. However, very little is known about circular granular ratchets, startling devices able to convert vertical vibrations into rotations of the device. Here, we report results of systematic numerical investigations of the operational characteristics of circular granular ratchets. Several distinct behaviors are identified and explained in terms of the inner flow fields of the ratchet. All dynamical regimes found are robust and should not be difficult to observe in laboratory experiments.},
author = {Müller, Patric and Gallas, Jason and Pöschel, Thorsten},
doi = {10.1038/s41598-017-12588-w},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Dynamical} regimes and stability of circular granular ratchets},
volume = {7},
year = {2017}
}
@article{faucris.107033124,
abstract = {
Grid based fluid simulation methods are not able to solve complex non-linear dynamics like the rupture of a dynamic liquid bridge between freely colliding solids–an exemplary scenario of capillary forces competing with inertial forces in engineering applications–using a monolithic formulation for the solid and liquid phases present. We introduce a new Incompressible Smoothed Particle Hydrodynamics method for simulating three dimensional fluid-solid interaction flows with capillary (wetting and surface tension) effects at free surfaces. This meshless approach presents significant advantages over grid based approaches in terms of being monolithic and in handling interaction with free solids. The method is validated for accuracy and stability in dynamic scenarios involving surface tension and wetting. We then present three dimensional simulations of crown forming instability following the splash of a liquid drop, and the rupture of a liquid bridge between two colliding solid spheres, to show the method’s advantages in the study of dynamic micromechanical phenomena involving capillary flows.
},
author = {Nair, Prapanch and Pöschel, Thorsten},
doi = {10.1016/j.ces.2017.10.042},
faupublication = {yes},
journal = {Chemical Engineering Science},
pages = {192-204},
peerreviewed = {Yes},
title = {{Dynamic} capillary phenomena using {Incompressible} {SPH}},
volume = {176},
year = {2017}
}
@article{faucris.307432986,
author = {Roy, Sudeshna and Pöschel, Thorsten and Shaheen, Mohamad Yousef},
doi = {10.1007/s10035-023-01349-4},
faupublication = {yes},
journal = {Granular Matter},
peerreviewed = {Yes},
title = {{Effect} of cohesion on the structure of powder layers in additive manufacturing},
year = {2023}
}
@article{faucris.123972464,
abstract = {By means of particle-based numerical simulations using the discrete element method, we address the question of how the performance of granular dampers is affected by the shape of the granular particles. In consistence with previous experiments performed with nearly spherical particles we find that independently of the particles‘ shape, the granular system is characterized by a gas-like regime for small amplitudes of the container’s oscillation and by a collect-and-collide regime for large amplitude forcing. Both regimes are separated by an optimal operation mode—the critical amplitude of the damping oscillation for which the energy dissipation is maximal—which is independent of the particle shape for given conditions of particle mass, material properties and number of particles. However, in the gas-like regime, we find that spherical particles lead to more efficient energy dissipation compared to complex shaped particles of the same mass. In this regime, a dependence on the damper’s efficiency on the particle shape is found.},
author = {Pourtavakoli, Hamzeh and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1088/1367-2630/18/7/073049},
faupublication = {yes},
journal = {New Journal of Physics},
peerreviewed = {Yes},
title = {{Effect} of particle shape on the efficiency of granular dampers},
volume = {18},
year = {2016}
}
@article{faucris.288790122,
abstract = {Abstract: Granular grippers are highly adaptable end-effectors that exploit the reversible jamming transition of granular materials to hold and manipulate objects. Their holding force comes from the combination of three mechanisms: frictional forces, geometrical constraints, and suction effects. In this work, we experimentally study the effect of particle size on the suction mechanism. Through X-ray computed tomography, we show that small particles (average diameter d≈120μm) achieve higher conformation around the object than larger particles (d≈4mm), thus allowing the formation of air-tight seals. When the gripper is pulled off, mimicking lifting of an object, vacuum pressure is generated in the sealed cavity at the interface gripper–object. If the particles used as filling material are too large, the gripper does not conform closely around the object, leaving gaps between the gripper’s membrane and the object. These gaps prevent the formation of sealed vacuum cavities between the object and the gripper and in turn hinder the suction mechanism from operating. Graphical abstract: [Figure not available: see fulltext.]},
author = {Santarossa, Angel and D'Angelo, Olfa and Sack, Achim and Pöschel, Thorsten},
doi = {10.1007/s10035-022-01306-7},
faupublication = {yes},
journal = {Granular Matter},
keywords = {Computed tomography; Granular gripper; Jamming transition; Soft robotics; Suction},
note = {CRIS-Team Scopus Importer:2023-02-03},
peerreviewed = {Yes},
title = {{Effect} of particle size on the suction mechanism in granular grippers},
volume = {25},
year = {2023}
}
@inproceedings{faucris.106410964,
abstract = {
Part of the optimization steps for the additive manufacturing is related to the correct understanding of the mechanical behavior of the powder used in the process. Numerical simulations through the Discrete Element Method (DEM) provide a useful means to investigate additive manufacturing process thus assisting and complementing experimental investigations. In particular, with the help of DEM simulations, it is possible to study particle-scale processes that are difficult to access experimentally. We investigate the characteristics of the powder bed deposited onto the manufactured part using a roller as the coating system. Furthermore, the non-spherical shape of real particles is also taken explicitly into account in the numerical simulations. A combination of translational velocity and sinusoidal vibration is used in the roller. The effect of varying the translational velocity, vibration frequency and amplitude in the density and roughness of the formed bed is investigated.
},
address = {Ljubljana},
author = {Schiochet Nasato, Daniel and Pöschel, Thorsten and Ribeiro Parteli, Eric Josef},
booktitle = {6th International Conference on Additive Technologies iCAT},
date = {2016-11-29/2016-11-30},
editor = {Drstvenšek I, Drummer D, Schmidt M},
faupublication = {yes},
isbn = {978-961-285-537-6},
peerreviewed = {unknown},
publisher = {Interesansa - zavod},
title = {{Effect} of vibrations applied to the transport roller in the quality of the powder bed during additive manufacturing},
venue = {Nürnberg},
year = {2016}
}
@article{faucris.106904424,
abstract = {
We consider electroconvection as the response of nematic liquid crystal to an external electric AC field, in the absence of free charge carriers. Previous experimental and theoretical results emphasized charge carriers as a necessary precondition of electroconvection because free-charges in the fluid can response to the external electric field. Therefore, ionized molecules are considered as responsible for the driving of electroconvective flows. In experiments, finite conductivity is achieved by adding charge-carrying dye molecules or in non-dyed liquid crystals by impurities of the samples. The phenomenon of electroconvection is explained by the Carr-Helfrich theory, supported by numerical simulations. In the present paper, we show that electroconvection may occur also in pure nematic liquid crystals. By means of particle-based numerical simulation we found that bound charges emerge by alignment of polarized liquid crystal molecules in response to the external electric field. In our simulations we could reproduce the characteristic features of electroconvection, such as directorflow patterns, the phase-transition in the voltage-frequency diagram, and dislocation climb/glide motion, which are well known from experiments and hydrodynamic simulations under the assumption of free charge carriers.
},
author = {Lee, Kuang-Wu and Pöschel, Thorsten},
doi = {10.1039/C7SM02055D},
faupublication = {yes},
journal = {Soft Matter},
pages = {8816-8823},
peerreviewed = {unknown},
title = {{Electroconvection} of {Pure} {Nematic} {Liquid} {Crystals} without {Free} {Charge} {Carriers}},
volume = {120},
year = {2017}
}
@incollection{faucris.218987059,
abstract = {Quantum statistics is a many body theory describing macroscopic matter. Let us first summarize concepts of classical many body theory and subsequently concepts of many body quantum theory, just what we need in the following. After this we will proceed to the simplest quantum statistical ensembles.},
address = {Cham},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3{\_}2},
faupublication = {yes},
isbn = {978-3-030-05733-6},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {19-53},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Elements} of quantum statistical theory},
volume = {953},
year = {2019}
}
@article{faucris.109180984,
abstract = {An inelastic hard ball bouncing repeatedly off the ground comes to rest in finite time by performing an infinite number of collisions. Similarly, a granular gas under the influence of external gravity, condenses at the bottom of the confinement due to inelastic collisions. By means of hydrodynamical simulations, we find that the condensation process of a granular gas reveals a similar dynamics as the bouncing ball. Our result is in agreement with both experiments and particle simulations, but disagrees with earlier simplified hydrodynamical description. Analyzing the result in detail, we find that the adequate modeling of pressure plays a key role in continuum modeling of granular matter.},
author = {Almazan Torres, Lidia and Serero, Dan and Salueña, Clara and Pöschel, Thorsten},
doi = {10.1088/1367-2630/aa5598},
faupublication = {yes},
journal = {New Journal of Physics},
month = {Jan},
peerreviewed = {Yes},
title = {{Energy} decay in a granular gas collapse},
volume = {19},
year = {2017}
}
@article{faucris.119184384,
abstract = {We experimentally investigate the energy dissipation rate in sinusoidally driven boxes which are partly filled by granular material under conditions of weightlessness. We identify two different modes of granular dynamics, depending on the amplitude of driving, A. For intense forcing, A>A, the material is found in the collect-and-collide regime where the center of mass of the granulate moves synchronously with the driven container, while for weak forcing, A},
author = {Sack, Achim and Heckel, Michael and Kollmer, Jonathan and Zimber, Fabian and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.111.018001},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Energy} dissipation in driven granular matter in the absence of gravity},
volume = {111},
year = {2013}
}
@article{faucris.109923264,
author = {Brilliantov, Nikolai V. and Pöschel, Thorsten},
doi = {10.1209/epl/i2006-10099-3},
faupublication = {no},
journal = {EPL - Europhysics Letters},
peerreviewed = {Yes},
title = {{Erratum}: {Breakdown} of the sonine expansion for the velocity distribution of granular gases ({Europhysics} {Letters} (2006) 74:3 (424-430) )},
volume = {75},
year = {2006}
}
@article{faucris.109829104,
author = {Brilliantov, Nikolai V. and Albers, Nicole and Spahn, Frank and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.87.039904},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Erratum}: {Collision} dynamics of granular particles with adhesion ({Physical} {Review} {E} (2007) 76 (051302))},
volume = {87},
year = {2013}
}
@article{faucris.109843844,
author = {Meerson, Baruch and Pöschel, Thorsten and Sasorov, Pavel V. and Schwager, Thomas},
doi = {10.1103/PhysRevE.69.059905},
faupublication = {no},
journal = {Physical Review E},
pages = {059905-1},
peerreviewed = {Yes},
title = {{Erratum}: {Giant} fluctuations at a granular phase separation threshold ({Physical} {Review} {E} (2004) 69 (021302))},
url = {http://journals.aps.org/pre/abstract/10.1103/PhysRevE.69.059905},
volume = {69},
year = {2004}
}
@article{faucris.267373490,
abstract = {The original version of this Article contained an error in Fig. 5. In Fig. 5e, the scale on the y-axis originally incorrectly went from '0' to '1.10-4'. The correct scale goes from '0' to '0.4'. In Fig 5f, the x-axis labels were incorrectly shifted to the right. This has been corrected in both the PDF and HTML versions of the Article.},
author = {Scholz, Christian and Engel, Michael and Pöschel, Thorsten},
doi = {10.1038/s41467-018-03873-x},
faupublication = {yes},
journal = {Nature Communications},
note = {CRIS-Team Scopus Importer:2021-12-22},
pages = {1497-},
peerreviewed = {Yes},
title = {{Erratum}: {Publisher} {Correction}: {Rotating} robots move collectively and self-organize ({Nature} communications (2018) 9 1 (931))},
volume = {9},
year = {2018}
}
@article{faucris.109027644,
abstract = {In [1] the rotational frequency of a single Vibrot was incorrectly plotted as a function
of the excitation amplitude A. Instead the figure shows the data in dependence of the
dimensionless acceleration Γ= A(2πƒD)2/g, where g is the gravitational acceleration.
Only in the case of ƒD = 50 Hz A = 0.13 mm corresponds to Γ = 1.3 g and vice versa.
The corresponding paragraph of the original manuscript must then be replaced by the
following: „Figure 4 shows ϖ vs. ƒD for two different values of the dimensionless
acceleration Γ = A(2πƒD)2/g. For a low Γ the particle performs slow rotation where
ƒD depends non-monotonously on the frequency characterized by a minimum at ƒD = 50
Hz. For large Γ, we observe slow rotation at low frequency and tumbling motion for
ƒD ≥ 30 Hz, where the rotational velocity decreases with increasing ƒD.“ The
corrected version of the plot is shown in Fig. 4.},
author = {Scholz, Christian and Pöschel, Thorsten},
faupublication = {yes},
journal = {Revista Cubana de Fisica },
peerreviewed = {unknown},
title = {{Erratum} to: {Actively} {Rotating} {Granular} {Particles} {Manufactured} by {Rapid} {Prototyping}},
volume = {33},
year = {2016}
}
@article{faucris.270674525,
author = {Wenzel, Tim and Sack, Achim and Müller, Patric and Pöschel, Thorsten and Schuldt-Lieb, Sonja and Gieseler, Henning},
doi = {10.1093/jpp/rgab174},
faupublication = {yes},
journal = {Journal of Pharmacy and Pharmacology},
note = {CRIS-Team Scopus Importer:2022-03-11},
pages = {458-},
peerreviewed = {Yes},
title = {{Erratum} to: {Stability} of freeze-dried products subjected to microcomputed tomography radiation doses},
volume = {74},
year = {2022}
}
@article{faucris.109168004,
abstract = {The original publication of the article contains an error in line number 8 of Algorithm 2. The correct version of the Algorithm 2 is provided in this erratum.},
author = {Strobl, Severin and Bannerman, Marcus and Pöschel, Thorsten},
doi = {10.1007/s40571-016-0111-x},
faupublication = {yes},
journal = {Computational Particle Mechanics},
peerreviewed = {Yes},
title = {{Erratum} to: {Stable} algorithm for event detection in event-driven particle dynamics: logical states},
url = {http://www.mss.cbi.fau.de/content/uploads/Erratum{\_}stable{\_}algorithm{\_}Computational{\_}Partical{\_}Mechanics{\_}2016.pdf},
year = {2016}
}
@inproceedings{faucris.109844724,
abstract = {In this paper an algorithm is described which combines the efficiency of event-driven Molecular-Dynamics (eMD) and the physical correctness of force-based Molecular-Dynamics (MD) for dilute granular systems of frictionless spheres. © 2013 AIP Publishing LL},
author = {Pöschel, Thorsten and Müller, Patric},
booktitle = {7th International Conference on Micromechanics of Granular Media: Powders and Grains 2013},
doi = {10.1063/1.4811889},
faupublication = {yes},
isbn = {9780735411661},
keywords = {event-driven Molecular-Dynamics; granular Gases; hard-sphere model; Molecular-Dynamics},
pages = {149-152},
title = {{Event}-driven {DEM} of soft spheres},
venue = {Sydney, NSW},
volume = {1542},
year = {2013}
}
@article{faucris.122877744,
abstract = {The dynamics of dissipative soft-sphere gases obeys Newton's equations of motion, which are commonly solved numerically by (force-based) Molecular Dynamics (MD) schemes. With the assumption of instantaneous, pairwise collisions, the simulation can be accelerated considerably using event-driven MD, where the coefficient of restitution is derived from the interaction force between particles. Recently it was shown, however, that this approach may fail dramatically, that is, the obtained trajectories deviate significantly from the ones predicted by Newton's equations. In this paper, we generalize the concept of the coefficient of restitution and derive a numerical scheme which, in the case of dilute systems and frictionless interaction, allows us to perform highly efficient event-driven MD simulations even for noninstantaneous collisions. We show that the particle trajectories predicted by our scheme agree perfectly with the corresponding (force-based) MD, except for a short transient period whose duration corresponds to the duration of the contact. Thus, the new algorithm solves Newton's equations of motion like force-based MD while preserving the advantages of event-driven simulations. © 2013 American Physical Society.},
author = {Müller, Patric and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.87.033301},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Event}-driven molecular dynamics of soft particles},
volume = {87},
year = {2013}
}
@article{faucris.114764804,
abstract = {An algorithm for the exact calculation of the overlap volume of a sphere and a tetrahedron, wedge, or hexahedron is described. The method can be used to determine the exact local solid fractions for a system of spherical, non-overlapping particles contained in a complex mesh, a question of significant relevance for the numerical solution of many fluid-solid interaction problems. While challenging due to the limited machine precision, a numerically robust version of the calculation maintaining high computational efficiency is devised. The method is evaluated with respect to the numerical precision and computational cost. It is shown that the exact calculation is only limited by the machine precision and can be applied to a wide range of size ratios, contrary to previously published methods. Eliminating this constraint enables the usage of meshes with higher resolution near the system boundaries for coupled CFD-DEM simulations. The numerical robustness is further illustrated by applying the method to highly deformed mesh elements. The full source code of the reference implementation is made available under an open-source license.},
author = {Strobl, Severin and Formella, Arno and Pöschel, Thorsten},
doi = {10.1016/j.jcp.2016.02.003},
faupublication = {yes},
journal = {Journal of Computational Physics},
keywords = {Local solid fraction; Numerical robustness; Overlap volume; Sphere-mesh overlap},
pages = {158-172},
peerreviewed = {Yes},
title = {{Exact} calculation of the overlap volume of spheres and mesh elements},
volume = {311},
year = {2016}
}
@article{faucris.109923924,
abstract = {The transmission of kinetic energy through chains of inelastically colliding spheres is investigated for the case of constant coefficient of restitution ε=const and impact-velocity-dependent coefficient ε(υ) for viscoelastic particles. We derive a theory for the optimal distribution of particle masses which maximize the energy transfer along the chain and check it numerically. We found that for ε=const, the mass distribution is a monotonous function which does not depend on the value of ε. In contrast, for ε(υ) the mass distribution reveals a pronounced maximum, depending on the particle properties and on the chain length. The system investigated demonstrates that even for small and simple systems, the velocity dependence of the coefficient of restitution may lead to new effects with respect to the same systems under the simplifying approximation ε=const. ©2001 The American Physical Society.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai},
doi = {10.1103/PhysRevE.63.021505},
faupublication = {no},
journal = {Physical Review E},
pages = {1-9},
peerreviewed = {Yes},
title = {{Extremal} collision sequences of particles on a line: {Optimal} transmission of kinetic energy},
volume = {63},
year = {2001}
}
@article{faucris.106400624,
abstract = {
As an environment for rich pattern formation, the electroconvection (EC) of nematic liquid crystals (LCs) is studied via fully nonlinear simulations for the first time. Previously, EC was mostly studied by experiments or
by linear/weakly nonlinear hydrodynamic theory for its instability criteria. While the negative dielectric LCs are used in most EC analytical and experimental investigations, EC with positive dielectric LCs is limited to
experiments only, due to their more complex nonlinear behavior. In this work we take a step beyond the existing weakly nonlinear EC research by using a fully nonlinear particle-based simulation. To investigate
the distinct dynamics of positive and negative dielectric LCs, we modified the molecular potential in the LC stochastic rotational model (LC SRD) [Lee et al., J. Chem. Phys., 2015, 142, 164110] to incorporate the
dielectric characteristics and the field-particle interaction. As a result, different convection patterns known in the EC experiments were observed in our simulations, for which those patterns appeared orderly, as a function of external field strength. The simulated director and flow fields correspond to each other well, as found in our experiments. For the positive dielectric LC, we discovered a net directional flow accompanying the travelling EC rolls. This numerical model and its hydrodynamic analysis could be used for precise flow control at the micro-scale, such as nematic colloidal transportation in microfluidics.
},
author = {Lee, Kuang-Wu and Pöschel, Thorsten},
doi = {10.1039/C7RA06757G},
faupublication = {yes},
journal = {RSC Advances},
peerreviewed = {unknown},
title = {{Field}-driven pattern formation in nematic liquid crystals: mesoscopic simulations of electroconvection},
volume = {7},
year = {2017}
}
@article{faucris.265055571,
abstract = {Many experimental studies revealed subdiffusion of various nanoparticles in diverse polymer and colloidal solutions, cytosol and plasma membrane of biological cells, which are viscoelastic and, at the same time, highly inhomogeneous randomly fluctuating environments. The observed subdiffusion often combines features of ergodic fractional Brownian motion (reflecting viscoelasticity) and nonergodic jumplike non-Markovian diffusional processes (reflecting disorder). Accordingly, several theories were proposed to explain puzzling experimental findings. Below we show that some of the significant and profound published experimental results are better rationalized within the viscoelastic subdiffusion approach in random environments, which is based on generalized Langevin dynamics in random potentials, than some earlier proposed theories.},
author = {Goychuk, Igor and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.104.034125},
faupublication = {yes},
journal = {Physical Review E},
note = {CRIS-Team WoS Importer:2021-10-15},
peerreviewed = {Yes},
title = {{Fingerprints} of viscoelastic subdiffusion in random environments: {Revisiting} some experimental data and their interpretations},
volume = {104},
year = {2021}
}
@article{faucris.246386861,
abstract = {This work justifies further paradigmatic importance of the model of viscoelastic subdiffusion in random environments for the observed subdiffusion in cellular biological systems. Recently, we showed (2018, PCCP, 20, 24140) that this model displays several remarkable features, which makes it an attractive paradigm to explain the physical nature of subdiffusion occurring in biological cells. In particular, it combines viscoelasticity with distinct non-ergodic features. We extend this basic model to make it suitable for physical phenomena such as subdiffusion of lipids in disordered biological membranes upon including the inertial effects. For lipids, the inertial effects occur in the range of picoseconds, and a power-law decaying viscoelastic memory extends over the range of several nanoseconds. Thus, in the absence of disorder, diffusion would become normal on a time scale beyond this memory range. However, both experimentally and in some molecular-dynamical simulations, the time range of lipid subdiffusion extends far beyond the viscoelastic memory range. We study three 1d models of correlated quenched Gaussian disorder to explain the puzzle: singular short-range (exponentially correlated), smooth short-range (Gaussian-correlated), and smooth long-range (power-law correlated) disorder. For a moderate disorder strength, transient viscoelastic subdiffusion changes into the subdiffusion caused by the randomness of the environment. It is characterized by a time-dependent power-law exponent of subdiffusion alpha(t), which can show nonmonotonous behavior, in agreement with some recent molecular-dynamical simulations. Moreover, the spatial distribution of test particles in this disorder-dominated regime is shown to be a non-Gaussian, exponential power distribution with index chi = 1.45-2.3, which also correlates well with molecular-dynamical findings and experiments. Furthermore, this subdiffusion is nonergodic with single-trajectory averages showing a broad scatter, in agreement with experimental observations for viscoelastic subdiffusion of various particles in living cells.},
author = {Goychuk, Igor and Pöschel, Thorsten},
doi = {10.1088/1367-2630/abc603},
faupublication = {yes},
journal = {New Journal of Physics},
note = {CRIS-Team WoS Importer:2020-12-04},
peerreviewed = {Yes},
title = {{Finite}-range viscoelastic subdiffusion in disordered systems with inclusion of inertial effects},
volume = {22},
year = {2020}
}
@article{faucris.109929204,
abstract = {Given an equidistribution for probabilities p(i) -1/N, i = 1,...,N. What is the expected corresponding rank ordered frequency distribution f(i), i=1,...,N, if an ensemble of M events is drawn? © 2002 The American Physical Society.},
author = {Pöschel, Thorsten and Freund, Jan A.},
doi = {10.1103/PhysRevE.66.026103},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Finite}-sample frequency distributions originating from an equiprobability distribution},
url = {http://journals.aps.org/pre/abstract/10.1103/PhysRevE.66.026103},
volume = {66},
year = {2002}
}
@article{faucris.257708672,
abstract = {The main mechanism driving rheological transitions is usually mechanical perturbation by shear unjamming mechanism. Investigating discontinuous shear thickening is challenging because the shear counterintuitively acts as a jamming mechanism. Moreover, at the brink of this transition, a thickening material exhibits fluctuations that extend both spatially and temporally. Despite recent extensive research, the origins of such spatiotemporal fluctuations remain unidentified. Here, we numerically investigate the fluctuations in injected power in discontinuous shear thickening in granular materials. We show that a simple fluctuation relation governs the statistics of power fluctuations. Furthermore, we reveal the formation of like-torque clusters near thickening and identify an unexpected relation between the spatiotemporal fluctuations and the collective behavior due to the formation of like-torque clusters. We expect that our general approach should pave the way to unmasking the origin of spatiotemporal fluctuations in discontinuous shear thickening.},
author = {Rahbari, S. H. E. and Otsuki, Michio and Pöschel, Thorsten},
doi = {10.1038/s42005-021-00574-8},
faupublication = {yes},
journal = {Communications Physics},
note = {CRIS-Team WoS Importer:2021-05-07},
peerreviewed = {Yes},
title = {{Fluctuations} and like-torque clusters at the onset of the discontinuous shear thickening transition in granular materials},
volume = {4},
year = {2021}
}
@article{faucris.109808424,
abstract = {We consider the transition of a horizontally vibrated monodisperse granular monolayer between its condensed state and its three-dimensional gaseous state as a function of the vibration parameters, amplitude, and frequency as well as particle number density. The transition is characterized by an abrupt change of the dynamical state which leaves its fingerprints in several measurable quantities including dissipation rate, sound emission, and a gap size which characterizes the sloshing motion of the material. The transition and its pronounced hysteresis is explained through the energy due to the collective motion of the particles relative to the container.},
author = {Heckel, Michael and Sack, Achim and Kollmer, Jonathan and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.91.062213},
faupublication = {yes},
journal = {Physical Review E - Statistical, Nonlinear, and Soft Matter Physics},
peerreviewed = {Yes},
title = {{Fluidization} of a horizontally driven granular monolayer},
volume = {91},
year = {2015}
}
@article{faucris.122142504,
abstract = {In dense, static, polydisperse granular media under isotropic pressure, the probability density and the correlations of particle-wall contact forces are studied. Furthermore, the probability density functions of the populations of pressures measured with different sized circular pressure cells are examined. The questions answered are: (i) What is the number of contacts that has to be considered so that the measured pressure lies within a certain error margin from its expectation value? (ii) What is the statistics of the pressure probability density as function of the size of the pressure cell? Astonishing non-random correlations between contact forces are evidenced that lead to a rapid decay of the width of the distribution and range at least 10-15 particle diameters. Finally, an experiment is proposed to tackle and better understand this issue. © 2010 Elsevier B.V. All rights reserved.},
author = {Müller, Micha-Klaus and Luding, Stefan and Pöschel, Thorsten},
doi = {10.1016/j.chemphys.2010.07.020},
faupublication = {yes},
journal = {Chemical Physics},
keywords = {DEM simulations; Dense static granular packings; Force and stress correlations; Pressure cells},
pages = {600-605},
peerreviewed = {Yes},
title = {{Force} statistics and correlations in dense granular packings},
volume = {375},
year = {2010}
}
@article{faucris.119753304,
abstract = {The structural evolution of a nanopowder by repeated dispersion and settling can lead to characteristic fractal substructures. This is shown by numerical simulations of a two-dimensional model agglomerate of adhesive rigid particles. The agglomerate is cut into fragments of a characteristic size , which then are settling under gravity. Repeating this procedure converges to a loosely packed structure, the properties of which are investigated: (a)The final packing density is independent of the initialization, (b) the short-range correlation function is independent of the fragment size, (c) the structure is fractal up to the fragmentation scale with a fractal dimension close to 1.7, and (d) the relaxation time increases linearly with. © 2008 The American Physical Society.},
author = {Schwager, Thomas and Wolf, Dietrich E. and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.100.218002},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Fractal} substructure of a nanopowder},
volume = {100},
year = {2008}
}
@article{faucris.122800744,
abstract = {Packings of cohesive nanoparticles, that is nano powders, may be obtained as the result of repeated fragmentation–reagglomeration cycles (Schwager et al. in Phys Rev Lett 100:218002, 2008) such that the resulting sediment reveals a fractal structure. The size distribution of the fragments after a fragmentation step is a superposition of a narrow distribution of large particles (chunks) whose size is determined by the cutting length and a power-law distribution for small particles, representing scale invariant dust. It was shown that the exponent of the power-law, τ , is in non-trivial relation to the fractal dimension, d f , via d f (2 − τ ) = 1. This poses the question for the structure of the sediment created by repeated fragmentation–reagglomeration cycles when the dust particles are excluded from the reagglomeration step. We found that even in this case, repeated fragmentation-reagglomeration cycles yield a sediment of fractal structure with slightly reduced fractal dimension while the dust exponent, τ , remains unchanged.},
author = {Topic, Nikola and Wolf, Dietrich E. and Pöschel, Thorsten},
doi = {10.1007/s10035-015-0601-1},
faupublication = {yes},
journal = {Granular Matter},
peerreviewed = {Yes},
title = {{Fractal} {Substructure} of a nanopowder generated by repeated fragmentation and sedimentation: {The} role of the dust},
year = {2016}
}
@inproceedings{faucris.109930524,
abstract = {Cohesive powders form agglomerates that can be very porous. Hence they are also very fragile. Consider a process of complete fragmentation on a characteristic length scale I, where the fragments are subsequently allowed to settle under gravity. If this fragmentation-reagglomeration cycle is repeated sufficiently often, the powder develops a fractal substructure with robust statistical properties. The structural evolution is discussed for two different models: The first one is an off-lattice model, in which a fragment does not stick to the surface of other fragments that have already settled, but rolls down until it finds a locally stable position. The second one is a simpler lattice model, in which a fragment sticks at first contact with the agglomerate of fragments that have already settled. Results for the fragment size distribution are shown as well. One can distinguish scale invariant dust and fragments of a characteristic size. Their role in the process of structure formation will be addressed. © 2009 American Institute of Physic},
author = {Wolf, D. E. and Pöschel, Thorsten and Schwager, T. and Weuster, A. and Brendel, L.},
booktitle = {6th International Conference on Micromechanics of Granular Media, Powders and Grains 2009},
doi = {10.1063/1.3180065},
faupublication = {yes},
isbn = {9780735406827},
keywords = {Fractals macroscopic aggregates; Granular systems; Pattern formation; Porous materials; Powders},
pages = {859-862},
title = {{Fractal} substructures due to fragmentation and reagglomeration},
venue = {Golden, CO},
volume = {1145},
year = {2009}
}
@article{faucris.266346803,
author = {Weinhart, Thomas and Lechman, Jeremy and Pöschel, Thorsten},
doi = {10.1007/s40571-021-00442-w},
faupublication = {yes},
journal = {Computational Particle Mechanics},
note = {CRIS-Team Scopus Importer:2021-11-19},
pages = {1003-1004},
peerreviewed = {Yes},
title = {{Fragmentation} and abrasion in granular matter systems},
volume = {8},
year = {2021}
}
@article{faucris.122902824,
abstract = {The phase separation instability that occurs in a system of nearly elastically colliding hard spheres driven by a thermal wall was investigated. It was demonstrated that if the aspect ratio of the confining box exceeded a threshold value the phase separation could be predicted by granular hydrostatics. It was found that in a wide region of aspect ratios around the threshold, the system was dominated by fluctuations. The two possible scenarios of the origin of the giant fluctuations were also discussed.},
author = {Meerson, Baruch and Pöschel, Thorsten and Sasorov, Pavel V. and Schwager, Thomas},
doi = {10.1103/PhysRevE.69.021302},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Giant} fluctuations at a granular phase separation threshold},
volume = {69},
year = {2004}
}
@article{faucris.306936550,
abstract = {Granular dampers are systems used to attenuate undesired vibrations produced by mechanical devices. They consist of cavities filled by granular particles. In this work, we consider a granular damper filled with a binary mixture of frictionless spherical particles of the same material but different size using numerical discrete element method simulations. We show that the damping efficiency is largely influenced by the composition of the binary mixture.},
author = {Varela Rosales, Nydia and Santarossa, Angel and Engel, Michael and Pöschel, Thorsten},
doi = {10.1007/s10035-023-01337-8},
faupublication = {yes},
journal = {Granular Matter},
keywords = {Energy dissipation; Granular damper; Granular mixtures; Vibration},
note = {CRIS-Team Scopus Importer:2023-06-30},
peerreviewed = {Yes},
title = {{Granular} binary mixtures improve energy dissipation efficiency of granular dampers},
volume = {25},
year = {2023}
}
@article{faucris.117769124,
abstract = {
By means of particle-based numerical simulations using the discrete element method, we address the
question of how the performance of granular dampers is affected by the shape of the granular particles.
In consistence with previous experiments performed with nearly spherical particles we
fi
nd that
independently of the particles
’
shape, the granular system is characterized by a gas-like regime for
small amplitudes of the container
’
s oscillation and by a collect-and-collide regime for large amplitude
forcing. Both regimes are separated by an optimal operation mode
—
the critical amplitude of the
damping oscillation for which the energy dissipation is maximal
—
which is independent of the particle
shape for given conditions of particle mass, material properties and number of particles. However, in
the gas-like regime, we
fi
nd that spherical particles lead to more ef
fi
cient energy dissipation compared
to complex shaped particles of the same mass. In this regime, a dependence on the damper
’
sef
fi
ciency
on the particle shape is found.
},
author = {Pourtavakoli, Hamzeh and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1088/1367-2630/18/7#/073049},
faupublication = {yes},
journal = {New Journal of Physics},
keywords = {granular matter, numerical simulations, discrete element method, granular dampers},
peerreviewed = {Yes},
title = {{Granular} dampers: does particle shape matter?},
volume = {18},
year = {2016}
}
@article{faucris.119660464,
abstract = {Instruments for surgical and dental application based on oscillatory mechanics submit unwanted vibrations to the operator's hand. Frequently the weight of the instrument's body is increased to dampen its vibration. Based on recent research regarding the optimization of granular damping we developed a prototype granular damper that attenuates the vibrations of an oscillatory saw twice as efficiently as a comparable solid mass. © 2012 Elsevier B.V. All rights reserved.},
author = {Heckel, Michael and Sack, Achim and Kollmer, Jonathan and Pöschel, Thorsten},
doi = {10.1016/j.physa.2012.04.007},
faupublication = {yes},
journal = {Physica A-Statistical Mechanics and Its Applications},
keywords = {Dissipation mechanism; Granular damper; Granular system; Vibrations},
pages = {4442-4447},
peerreviewed = {Yes},
title = {{Granular} dampers for the reduction of vibrations of an oscillatory saw},
volume = {391},
year = {2012}
}
@article{faucris.238602625,
abstract = {When a container filled with granular material is subjected to sinusoidal vibration in microgravity, dependent on the amplitude of the oscillation, the granulate may exhibit one of two distinct dynamical modes: at low amplitude, a gas-like state is observed, where the particles are relatively homogeneously distributed within the container, almost independent of the phase of the oscillation. In contrast, for large amplitude, collective motion of the particles is favoured, termed collect-and-collide regime. Both regimes are characterized by very different dissipation characteristics. A recent model predicts that the regimes are separated by a sharp transition due to a critical amplitude of the vibration. Here we confirm this prediction of a sharp transition and also the numerical value of the critical amplitude by means of experiments performed under conditions of weightlessness.},
author = {Sack, Achim and Windows-Yule, Kit and Heckel, Michael and Werner, Dominik and Pöschel, Thorsten},
doi = {10.1007/s10035-020-01017-x},
faupublication = {yes},
journal = {Granular Matter},
note = {CRIS-Team WoS Importer:2020-05-22},
peerreviewed = {Yes},
title = {{Granular} dampers in microgravity: sharp transition between modes of operation},
volume = {22},
year = {2020}
}
@article{faucris.109937124,
abstract = {We present a universal description of the velocity distribution function of granular gases, f(v), valid for both, small and intermediate velocities where v is close to the thermal velocity and also for large v where the distribution function reveals an exponentially decaying tail. By means of large-scale Monte Carlo simulations and by kinetic theory we show that the deviation from the Maxwell distribution in the high-energy tail leads to small but detectable variation of the cooling coefficient and to extraordinary large relaxation time. © World Scientific Publishing Company.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai V. and Formella, Arno},
doi = {10.1142/S0129183107010966},
faupublication = {no},
journal = {International Journal of Modern Physics C},
keywords = {Granular gases; Overpopulated high-energy tail; Velocity distribution function},
pages = {701-711},
peerreviewed = {Yes},
title = {{Granular} gas cooling and relaxation to the steady state in regard to the overpopulated tail of the velocity distribution},
volume = {18},
year = {2007}
}
@article{faucris.123696144,
author = {Brey, Javier and Goldhirsch, Isaac and Pöschel, Thorsten},
faupublication = {yes},
journal = {European Physical Journal - Special Topics},
peerreviewed = {Yes},
title = {{Granular} {Gases}: {Beyond} the {Dilute} {Limit}},
volume = {179},
year = {2009}
}
@article{faucris.109937344,
abstract = {The goal of this study is to demonstrate numerically that certain hydrodynamic systems, derived from inelastic kinetic theory, give fairly good descriptions of rapid granular flows even if they are way beyond their supposed validity limits. A numerical hydrodynamic solver is presented for a vibrated granular bed in two dimensions. It is based on a highly accurate shock capturing state-of-the-art numerical scheme applied to a compressible Navier - Stokes system for granular flow. The hydrodynamic simulation of granular flows is challenging, particularly in systems where dilute and dense regions occur at the same time and interact with each other. As a benchmark experiment, we investigate the formation of Faraday waves in a two-dimensional thin layer exposed to vertical vibration in the presence of gravity. The results of the hydrodynamic simulations are compared with those of event-driven molecular dynamics and the overall quantitative agreement is good at the level of the formation and structure of periodic patterns. The accurate numerical scheme for the hydrodynamic description improves the reproduction of the primary onset of patterns compared to previous literature. To our knowledge, these are the first hydrodynamic results for Faraday waves in two-dimensional granular beds that accurately predict the wavelengths of the two-dimensional standing waves as a function of the perturbation's amplitude. Movies are available with the online version of the paper. © 2008 Cambridge University Press.},
author = {Carrillo, José A. and Pöschel, Thorsten and Salueña, Clara},
doi = {10.1017/S0022112007009792},
faupublication = {no},
journal = {Journal of Fluid Mechanics},
pages = {119-144},
peerreviewed = {Yes},
title = {{Granular} hydrodynamics and pattern formation in vertically oscillated granular disk layers},
volume = {597},
year = {2008}
}
@article{faucris.122040204,
abstract = {We investigate the impact of a granular jet on a finite target by means of particle simulations. The resulting hydrodynamic fields are compared with theoretical predictions for the corresponding flow of an incompressible and rotation-free fluid. The degree of coincidence between the field obtained from the discrete granular system and the idealized continuous fluid flow depends on the characteristics of the granular system, such as granularity, packing fraction, inelasticity of collisions, friction and target size. In certain limits we observe a granular-continuum transition under which the geometric and dynamic properties of the particle jet and the fluid jet become almost identical. © 2014 Cambridge University Press.},
author = {Müller, Patric and Formella, Arno and Pöschel, Thorsten},
doi = {10.1017/jfm.2014.210},
faupublication = {yes},
journal = {Journal of Fluid Mechanics},
keywords = {complex fluids; granular media; jets},
pages = {601-626},
peerreviewed = {Yes},
title = {{Granular} jet impact: {Probing} the ideal fluid description},
volume = {751},
year = {2014}
}
@article{faucris.241256751,
abstract = {When a container filled with granular material is subjected to vertical vibration in the presence of gravity, under certain conditions a non-monotonous density profile can be observed. This effect which is characteristic for dissipative granular gases, was termed “floating cluster regime” or “granular Leidenfrost effect”. Here, we study the behavior of vibro-agitated granular matter in the absence of gravity and identify a corresponding stationary state of the granulate, that is, we provide experimental evidence of the granular Leidenfrost effect under conditions of weightlessness.},
author = {Torres Menendez, Harol and Sack, Achim and Pöschel, Thorsten},
doi = {10.1007/s10035-020-01040-y},
faupublication = {yes},
journal = {Granular Matter},
keywords = {Floating cluster; Granular matter; Leidenfrost effect; Microgravity; Parabolic flight; Weightlessness; X-ray radiography},
note = {CRIS-Team Scopus Importer:2020-08-07},
peerreviewed = {Yes},
title = {{Granular} {Leidenfrost} effect in microgravity},
volume = {22},
year = {2020}
}
@article{faucris.119713044,
author = {Pöschel, Thorsten and Wolf, Dietrich},
faupublication = {yes},
journal = {Granular Matter},
peerreviewed = {Yes},
title = {{Granular} {Matter} - special edition},
volume = {14},
year = {2012}
}
@article{faucris.308521172,
abstract = {Jammed granular matter can be considered a meta-material that behaves viscoelastic for small deformations. We characterize the elastic properties of the meta-material through the response of a simply supported bending beam consisting of jammed granular matter under weak load and quasistatic deformation.
2+-mediated force were largely unaffected. Mutant single fibers showed tendencies towards faster unloaded shortening over wild type fibers. Effects of aging seen in the wild type appeared earlier in the mutant desmin fibers. Our single-fiber experiments, free of extracellular matrix, suggest that compromised muscle biomechanics is not exclusively attributed to fibrosis but also originates from an impaired intermediate filament network.},
author = {Pollmann, Charlotte and Haug, Michael and Reischl, Barbara and Prölß, Gerhard and Pöschel, Thorsten and Rupitsch, Stefan and Clemen, Christoph S. and Schröder, Rolf and Friedrich, Oliver},
doi = {10.3390/ijms21155501},
faupublication = {yes},
journal = {International Journal of Molecular Sciences},
keywords = {Biomechatronics; Desminopathy; R349P desmin; Single fibers; Skeletal muscle},
note = {CRIS-Team Scopus Importer:2020-08-14},
pages = {1-18},
peerreviewed = {Yes},
title = {{Growing} old too early: {Skeletal} muscle single fiber biomechanics in ageing r349p desmin knock-in mice using the myorobot technology},
volume = {21},
year = {2020}
}
@article{faucris.109942184,
abstract = {We propose a new method for the calculation of the statistical properties, e.g., the entropy, of unknown generators of symbolic sequences. The probability distribution p(k) of the elements k of a population can be approximated by the frequencies f(k) of a sample provided the sample is long enough so that each element k occurs many times. Our method yields an approximation if this precondition does not hold. For a given f(k) we recalculate the Zipf-ordered probability distribution by optimization of the parameters of a guessed distribution. We demonstrate that our method yields reliable results. © 1995 Plenum Publishing Corporation.},
author = {Pöschel, Thorsten and Ebeling, Werner and Rose, Helge},
doi = {10.1007/BF02179880},
faupublication = {no},
journal = {Journal of Statistical Physics},
keywords = {Entropy estimation; information science},
pages = {1443-1452},
peerreviewed = {Yes},
title = {{Guessing} probability distributions from small samples},
volume = {80},
year = {1995}
}
@article{faucris.109177024,
abstract = {Cylindrical containers with a rotating bottom disk (so-called split-bottom geometry) are well established devices to shear granular materials in a continuous way, and to generate well-defined localized shear bands in the granular bed. When material composed of shape-anisotropic grains is sheared in such a container, a secondary flow is generated that leads to the formation of a considerable heap of material near the rotation center. We demonstrate that this effect can be found not only with prolate grains, as shown in a previous study, but also for oblate particle shapes. In addition, the quantitative influence of geometric and dynamic parameters is studied systematically. It is shown that the fill height of the container has considerable influence on the time scale for heap formation, but much less effect on the heap height. Results of numerical simulations agree with the experimental findings and provide insight in the particle dynamics.},
author = {Börzsönyi, Tamás and Fischer, David and Schiochet Nasato, Daniel and Pöschel, Thorsten and Stannarius, Ralf},
doi = {10.1088/1367-2630/18/11/113006},
faupublication = {yes},
journal = {New Journal of Physics},
peerreviewed = {Yes},
title = {{Heaping} and secondary flows in sheared granular materials},
volume = {18},
year = {2016}
}
@article{faucris.122137004,
abstract = {Granular pipe flows are characterized by intermittent behavior and large, potentially destructive solid fraction variations in the transport direction. By means of particle-based numerical simulations of gravity-driven flows in vertical pipes, we show that it is possible to obtain steady material transport by adding a helical texture to the inner-wall of the pipe. The helical texture leads to a more homogeneous mass flux along the pipe, prevents the emergence of large density waves and substantially reduces the probability of plug formation thus avoiding jamming of the particulate flow. We show that the granular mass flux Q through a pipe of diameter D with a helical texture of wavelength λ follows the equation Q = Q0·{1 - Bsin[arctan(2πD/λ)]}, where Q0 is the flow without helix, predicted from the well-known Beverloo equation. Our new expression yields, thus, a modification of the Beverloo equation with only one additional fit parameter, B, and describes the particle mass flux with the helical texture with excellent quantitative agreement with simulation results. Future application of the method proposed here has the potential to improve granular pipe flows in a broad range of processes without the need for energy input from any external source.},
author = {Verbücheln, Felix and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1039/c5sm00760g},
faupublication = {yes},
journal = {Soft Matter},
pages = {4295-4305},
peerreviewed = {Yes},
title = {{Helical} inner-wall texture prevents jamming in granular pipe flows},
volume = {11},
year = {2015}
}
@article{faucris.119282284,
abstract = {
In this work, we examine theoretically the cooling dynamics of binary mixtures of spheres and rods. To this end, we introduce a generalized mean field analytical theory, which describes the free cooling behavior of the mixture. The relevant characteristic time scale for the cooling process is derived, depending on the mixture composition and the aspect ratio of the rods. We simulate mixtures of spherocylinders and spheres using a molecular dynamics algorithm implemented on graphics processing unit (GPU) architecture. We systematically study mixtures composed of spheres and rods with several aspect ratios and varying the mixture composition. A homogeneous cooling state, where the time dependence of the system’s intensive variables occurs only through a global granular temperature, is identified. We find cooling dynamics in excellent agreement with Haff’s law, when using an adequate time scale. Using the scaling properties of the homogeneous cooling dynamics, we estimated numerically the efficiency of the energy interchange between rotational and translational degrees of freedom for collisions between spheres and rods.
},
author = {Hidalgo, Raúl Cruz and Serero, Dan and Pöschel, Thorsten},
doi = {10.1063/1.4954670},
faupublication = {yes},
journal = {Physics of Fluids},
peerreviewed = {unknown},
title = {{Homogeneous} cooling of mixtures of particle shapes},
url = {http://www.mss.cbi.fau.de/content/uploads/Homogeneous{\_}cooling{\_}Physics{\_}of{\_}fluids{\_}2016.pdf},
volume = {28},
year = {2016}
}
@article{faucris.107691584,
abstract = {
We describe the velocity distribution function of a granular gas of electrically charged particles by means of a Sonine polynomial expansion and study the decay of its granular temperature. We find a dependence of the first non trivial Sonine coefficient, a2 , on time through the value of temperature. In particular, we find a sudden drop of a2 when temperature approaches a characteristic value, T∗ , describing the electrostatic interaction. For lower values of T , the velocity distribution function becomes Maxwellian. The theoretical calculations agree well with numerical Direct Simulation Monte Carlo, to validate our theory.
},
author = {Takada, Satoshi and Serero, Dan and Pöschel, Thorsten},
doi = {10.1063/1.4993620},
faupublication = {yes},
journal = {Physics of Fluids},
peerreviewed = {unknown},
title = {{Homogeneous} cooling state of dilute granular gases of charged particles},
volume = {29},
year = {2017}
}
@article{faucris.116252224,
abstract = {
We describe the velocity distribution function of a granular gas of electrically charged particles by means of a Sonine polynomial expansion and study the decay of its granular temperature. We find a dependence of the first non trivial Sonine coefficient, a2 , on time through the value of temperature. In particular, we find a sudden drop of a2 when temperature approaches a characteristic value, T∗, describing the electrostatic interaction. For lower values of T , the velocity distribution function becomes Maxwellian. The theoretical calculations agree well with numerical Direct Simulation Monte Carlo, to validate our theory.
},
author = {Takada, Satoshi and Serero, Dan and Pöschel, Thorsten},
doi = {10.1063/1.4993620},
faupublication = {yes},
journal = {Physics of Fluids},
peerreviewed = {unknown},
title = {{Homogeneous} cooling state of dilute granular gases of charged particles},
volume = {29},
year = {2017}
}
@article{faucris.119404604,
abstract = {The homogenization of granular flows through narrow pipes is important for a broad range of technological and industrial applications. Here we show, by means of molecular dynamics simulations, that such homogenization can be achieved by adding a helical inner-wall texture to the pipe, without the need for energy input from any external source. By using such a texture, jamming is prevented and the granular flux can be predicted using a modified Beverloo equation that accounts for the wavelength of the helical texture.},
author = {Verbücheln, Felix and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1051/epjconf/201714003069},
faupublication = {yes},
journal = {EPJ Web of Conferences},
peerreviewed = {unknown},
title = {{Homogenization} of granular pipe flow by means of helical inner-wall texture},
volume = {140},
year = {2017}
}
@article{faucris.109943944,
abstract = {In contrast to a still common belief, a steadily flowing hourglass changes its weight over the course of time (Shen and Scott in Am J Phys 53(8):787-788, 1985). We will show that, nevertheless, it is possible to construct hourglasses that do not change their weight. © 2007 Springer-Verlag.},
author = {Becker, Volker and Pöschel, Thorsten},
doi = {10.1007/s10035-007-0081-z},
faupublication = {no},
journal = {Granular Matter},
keywords = {Granular flow; Hour glass flow},
pages = {231-232},
peerreviewed = {Yes},
title = {{Hourglass} of constant weight},
volume = {10},
year = {2008}
}
@article{faucris.122088824,
abstract = {The decision whether a measured distribution complies with an equidistribution is a central element of many biostatistical methods. High throughput differential expression measurements, for instance, necessitate to judge possible over-representation of genes. The reliability of this judgement, however, is strongly affected when rarely expressed genes are pooled. We propose a method that can be applied to frequency ranked distributions and that yields a simple but efficient criterion to assess the hypothesis of equiprobable expression levels. By applying our technique to surrogate data we exemplify how the decision criterion can differentiate between a true equidistribution and a triangular distribution. The distinction succeeds even for small sample sizes where standard tests of significance (e.g. χ) fail. Our method will have a major impact on several problems of computational biology where rare events baffle a reliable assessment of frequency distributions. The program package is available upon request from the authors. © 2003 Elsevier Science Ireland Ltd. All rights reserved.},
author = {Pöschel, Thorsten and Freund, Jan A.},
doi = {10.1016/S0303-2647(03)00030-3},
faupublication = {no},
journal = {Biosystems},
keywords = {Biometrics; Finite sample statistics; Hypothesis testing; Microarray analysis},
pages = {63-72},
peerreviewed = {Yes},
title = {{How} to decide whether small samples comply with an equidistribution},
url = {http://www.sciencedirect.com/science/article/pii/S0303264703000303},
volume = {69},
year = {2003}
}
@article{faucris.228154248,
abstract = {When investigating dynamical processes in granular systems, it is frequently necessary to measure the time-resolved local material density. Recently, x-ray radiography facilities became available in many laboratories and can be used to measure the volume fraction via the attenuation of x-ray radiation along the beam direction. Naïve application of the Beer-Lambert law yields, however, unacceptably large systematic errors due to beam hardening. We present a calibration protocol which allows to reliably measure the local volume fraction based exclusively on reference measurement of known packing fraction.},
author = {Baur, Manuel and Claussen, Joelle and Gerth, Stefan and Kollmer, Jonathan and Shreve, Tara and Uhlmann, Norman and Pöschel, Thorsten},
doi = {10.1016/j.powtec.2019.08.025},
faupublication = {yes},
journal = {Powder Technology},
keywords = {Beam hardening; Volume fraction; X-ray radiography},
note = {CRIS-Team Scopus Importer:2019-10-22},
pages = {439-442},
peerreviewed = {Yes},
title = {{How} to measure the volume fraction of granular assemblies using x-ray radiography},
volume = {356},
year = {2019}
}
@inproceedings{faucris.106255204,
abstract = {The properties of dense granular systems are analyzed from a hydrodynamical point of view, based on conservation laws for the particle number density and linear momentum. We discuss averaging problems associated with the nature of such systems and the peculiarities of the sources of noise. We perform a quantitative study by combining analytical methods and numerical results obtained by ensemble-averaging of data on creep during compaction and molecular dynamics simulations of convective flow. We show that numerical integration of the hydrodynamic equations gives the expected evolution for the time-dependent fields.},
address = {Bellingham, WA, United States},
author = {Salueña, Clara and Esipov, Sergei E. and Pöschel, Thorsten},
booktitle = {Smart Structures and Materials 1997: Passive Damping and Isolation},
doi = {10.1117/12.274205},
faupublication = {no},
isbn = {0819424587},
pages = {2-11},
publisher = {Society of Photo-Optical Instrumentation Engineers},
title = {{Hydrodynamic} fluctuations and averaging problems in dense granular flows},
venue = {San Diego, CA, USA},
volume = {3045},
year = {1997}
}
@article{faucris.240997805,
abstract = {Hydrodynamic memory force or Basset force has been known since the 19th century. Its influence on Brownian motion remains, however, mostly unexplored. Here we investigate its role in nonlinear transport and diffusion within a paradigmatic model of tilted washboard potential. In this model, a giant enhancement of driven diffusion over its potential-free limit [Phys. Rev. Lett. 87, 010602 (2001)] presents a well-established paradoxical phenomenon. In the overdamped limit, it occurs at a critical tilt of vanishing potential barriers. However, for weak damping, it takes place surprisingly at another critical tilt, where the potential barriers are clearly expressed. Recently we showed [Phys. Rev. Lett. 123, 180603 (2019)] that Basset force could make such a diffusion enhancement enormously large. In this paper, we discover that even for moderately strong damping, where the overdamped theory works very well when the memory effects are negligible, substantial hydrodynamic memory unexpectedly makes a strong impact. First, the diffusion boost occurs at nonvanishing potential barriers and can be orders of magnitude larger. Second, transient anomalous diffusion regimes emerge over many time decades and potential periods. Third, particles' mobility can also be dramatically enhanced, and a long transient supertransport regime emerges.},
author = {Goychuk, Igor and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.102.012139},
faupublication = {yes},
journal = {Physical Review E},
note = {CRIS-Team WoS Importer:2020-07-31},
peerreviewed = {Yes},
title = {{Hydrodynamic} memory can boost enormously driven nonlinear diffusion and transport},
volume = {102},
year = {2020}
}
@article{faucris.109944604,
abstract = {The hydrodynamics of granular gases of viscoelastic particles were derived. Collisions of viscoelastic particles were characterized by an impact velocity dependent coefficient of restitution. The Chapman-Enskog approach was used together with an adiabatic approximation for the velocity distribution function, which assumes that the shape of the velocity distribution function follows adiabatically the decaying temperature. Numerical solutions for temperature T(t) and for the second Sonine coefficient a(t) were compared with the corresponding adiabatic approximations.},
author = {Brilliantov, Nikolai and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.67.061304},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Hydrodynamics} and transport coefficients for dilute granular gases},
url = {http://journals.aps.org/pre/abstract/10.1103/PhysRevE.67.061304},
volume = {67},
year = {2003}
}
@inproceedings{faucris.122142944,
abstract = {We perform two-dimensional hydrodynamic simulations on a paradigmatic problem of granular dynamics, the Faraday instability, using two different approximations to the Navier-Stokes granular equations: the constitutive equations and kinetic coefficients derived from the assumption of vanishing inelasticity (Jenkins-Richman approach) obtained by solving the Enskog equation disks by means of Grad's method, and the ones obtained by solving the Enskog equation with the Chapman-Enskog method (Garzó-Dufty-Lutsko approach). The comparison reveals important qualitative and quantitative differences with respect to the hydrodynamic fields obtained by averaging results from particle simulations of the same system. © 2012 American Institute of Physics.},
author = {Almazan Torres, Lidia and Salueña, Clara and Garzó, Vicente and Carrillo, José A. and Pöschel, Thorsten},
booktitle = {28th International Symposium on Rarefied Gas Dynamics 2012, RGD 2012},
doi = {10.1063/1.4769650},
faupublication = {yes},
isbn = {9780735411159},
keywords = {Faraday instability; hydrodynamic simulations; molecular dynamics; Rapid granular flows},
pages = {993-1000},
title = {{Hydrodynamics} at the {Navier}-{Stokes} level applied to fast, transient, supersonic granular flows},
venue = {Zaragoza},
volume = {1501},
year = {2012}
}
@article{faucris.122026784,
abstract = {A hydrodynamic description of dilute binary gas mixtures comprising smooth inelastic spheres interacting by binary collisions with a random coefficient of restitution is presented. Constitutive relations are derived using the Chapman-Enskog perturbative method, associated with a computer-aided method to allow high-order Sonine polynomial expansions. The transport coefficients obtained are checked against DSMC simulations. The resulting equations are applied to the analysis of a vertically vibrated system. It is shown that differences in the shape of the distributions of the coefficient of restitution are sufficient to produce partial segregation.},
author = {Pöschel, Thorsten and Serero, Dan and Gunkelmann, Nina},
doi = {10.1017/jfm.2015.501},
faupublication = {yes},
journal = {Journal of Fluid Mechanics},
keywords = {granular media; granular mixing; kinetic theory},
pages = {595-621},
peerreviewed = {unknown},
title = {{Hydrodynamics} of binary mixtures of granular gases with stochastic coefficient of restitution},
volume = {781},
year = {2015}
}
@article{faucris.119196924,
abstract = {Our study examines the long-time behaviour of a force-free granular gas of viscoelastic particles, for which the coefficient of restitution depends on the impact velocity, as it follows from the solution of the impact problem for viscoelastic spheres. Starting from the Boltzmann equation, we derived the hydrodynamic equations and obtained microscopic expressions for the transport coefficients in terms of the elastic and dissipative parameters of the particle material. We performed the stability analysis of the linearized set of equations and found that any inhomogeneities and vortices vanish after a long time and the system approaches the flow-free stage of homogeneous density. This behaviour is in contrast to that of a gas consisting of particles which interact via a (non-realistic) constant coefficient of restitution, for which inhomogeneities (clusters) and vortex patterns have been proven to arise and to continuously develop.},
author = {Brilliantov, Nikolai and Pöschel, Thorsten},
doi = {10.1098/rsta.2001.0940},
faupublication = {no},
journal = {Philosophical Transactions of the Royal Society A-Mathematical Physical and Engineering Sciences},
keywords = {Clustering; Dissipative gases; Granular gases; Hydrodynamics; Inelastic collisions; Structure formation},
pages = {415-428},
peerreviewed = {Yes},
title = {{Hydrodynamics} of granular gases of viscoelastic particles},
volume = {360},
year = {2002}
}
@incollection{faucris.218987307,
abstract = {Planck’s theory of radiation which is the origin of quantum statistics, was semi-phenomenological based on concepts of electrodynamics, classical thermodynamics, and classical radiation theory.},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3{\_}3},
faupublication = {yes},
isbn = {978-3-030-05734-3},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {55-90},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Ideal} quantum gases},
volume = {953},
year = {2019}
}
@article{faucris.240999055,
abstract = {In geotechnics as well as in planetary science, it is important to find a means by which to protect a base from impacts of micrometeoroids. In the moon, for example, covering a moon base with regolith, and housing such regolith by movable bounding walls, could work as a stress-leaking shield. Using a numerical model, by performing impacts on a granular material housed in a rectangular container made with one movable sidewall, it is found that such wall mobility serves as a good means for controlling the maximum force exerted at the container's base. We show that the force exerted at the container's base decreases as the movable wall decreases in mass, and it follows a Janssen-like trend. Moreover, by making use of a dynamically defined redirecting coefficient K (X), proposed by Windows-Yule et al. [Phys. Rev. E 100 , 022902 (2019)], which depends on the container's width X , we propose a model for predicting the maxima measured at the container's base. The model depends on the projectile and granulate properties, and the container's geometry.},
author = {Torres Cisneros, Luis Armando and Marzulli, Valentina and Windows-Yule, C. R. K. and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.102.012903},
faupublication = {yes},
journal = {Physical Review E},
note = {CRIS-Team WoS Importer:2020-07-31},
peerreviewed = {Yes},
title = {{Impact} in granular matter: {Force} at the base of a container made with one movable wall},
volume = {102},
year = {2020}
}
@article{faucris.119197584,
abstract = {The velocity distribution function of granular gases in the homogeneous cooling state as well as some heated granular gases decays for large velocities as fexp(-const×v). That is, its high-energy tail is overpopulated as compared with the Maxwell distribution. At the present time, there is no theory to describe the influence of the tail on the kinetic characteristics of granular gases. We develop an approach to quantify the overpopulated tail and analyze its impact on granular gas properties, in particular on the cooling coefficient. We observe and explain anomalously slow relaxation of the velocity distribution function to its steady state. © 2006 The American Physical Society.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai V. and Formella, Arno},
doi = {10.1103/PhysRevE.74.041302},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Impact} of high-energy tails on granular gas properties},
volume = {74},
year = {2006}
}
@article{faucris.232903043,
abstract = {The study of processes characterized by impulsive nature (i.e. impacts) can be considered of great interest in both physics and engineering disciplines: in the geotechnical field, for instance, their effect on the interaction between soil and structures need to be investigated. The present work aims at the validation, by means of two-dimensional finite element simulations, of a methodology of force calibration which uses results obtained from three-dimensional discrete element analysis for predicting the stress at the base of a granular bed, retained by a movable wall, arising when the system is hit by a projectile. To approach this problem, the low-velocity impact has been modeled as a punctual impulsive force on a granular packing.},
author = {Marzulli, Valentina and Torres Cisneros, Luis Armando and di Lernia, Annamaria and Windows-Yule, Christopher Robert Kit and Cafaro, Francesco and Pöschel, Thorsten},
doi = {10.1007/s10035-019-0988-1},
faupublication = {yes},
journal = {Granular Matter},
keywords = {Discrete element model; Finite element analysis; Granular material; Impact response; Numerical simulations; Soil–structure interaction},
note = {CRIS-Team Scopus Importer:2020-01-31},
peerreviewed = {Yes},
title = {{Impact} on granular bed: validation of discrete element modeling results by means of two-dimensional finite element analysis},
volume = {22},
year = {2020}
}
@article{faucris.107381824,
abstract = {The kinetic energy of a force-free granular gas decays monotonously due to inelastic collisions of the particles. For a homogeneous granular gas of identical particles, the corresponding decay of granular temperature is quantified by Haff’s law. Here, we report that for a granular gas of aggregating particles, the granular temperature does not necessarily decay but may even increase. Surprisingly, the increase of temperature is accompanied by the continuous loss of total gas energy. This stunning effect arises from a subtle interplay between decaying kinetic energy and gradual reduction of the number of degrees of freedom associated with the particles’ dynamics. We derive a set of kinetic equations of Smoluchowski type for the concentrations of aggregates of different sizes and their energies. We find scaling solutions to these equations and a condition for the aggregation mechanism predicting growth of temperature. Numerical direct simulation Monte Carlo results confirm the theoretical predictions.},
author = {Brilliantov, Nikolai and Formella, Arno and Pöschel, Thorsten},
doi = {10.1038/s41467-017-02803-7},
faupublication = {yes},
journal = {Nature Communications},
peerreviewed = {Yes},
title = {{Increasing} temperature of cooling granular gases},
volume = {9},
year = {2018}
}
@article{faucris.107287884,
abstract = {One of the most intensively discussed subjects in the dynamics of dissipative hard sphere systems is the effect of inelastic collapse, where the entire kinetic energy of the relative motion of a set of particles is dissipated in finite time due to an infinite sequence of collisions. The known collapse scenarios imply two preconditions: inertia of the particles and at least some degree of elasticity. For completely inelastic particles, collapse scenarios degenerate to a single sticky contact. By considering the overdamped motion of a frictional particle along the steepest descent in a rigid landscape, we will show that there exist collapse scenarios even if neither of these preconditions hold true. By means of numerical simulations we show that such collapses are no rare events due to particular particle shape and/or initial conditions and, thus, may lead to serious problems in article simulation},
author = {Topic, Nikola and Pöschel, Thorsten},
doi = {10.1038/s42005-019-0184-y},
faupublication = {yes},
journal = {Communications Physics},
peerreviewed = {Yes},
title = {{Inelastic} collapse of perfectly inelastic particles},
volume = {2},
year = {2019}
}
@article{faucris.122032504,
abstract = {Scattering experiments are fundamental for structure analysis of matter on molecular, atomic and sub-atomic length scales. In contrast, it is not standard to demonstrate optical scattering experiments on the undergraduate level beyond simple diffraction gratings. We present an inexpensive Mie scattering setup manufactured with 3D printing and open hardware. The experiment can be used to determine the particle size in dilute monodisperse colloidal suspensions with surprisingly high accuracy and is, thus, suitable to demonstrate relations between scattering measurements and microscopic properties of particles within undergraduate lab course projects.},
author = {Scholz, Christian and Sack, Achim and Heckel, Michael and Pöschel, Thorsten},
doi = {10.1088/0143-0807/37/5/055305},
faupublication = {yes},
journal = {European Journal of Physics},
keywords = {Mie scattering; physics education experiments; 3D printing; open hardware},
peerreviewed = {Yes},
title = {{Inexpensive} {Mie} scattering experiment for the classroom manufactured by {3D} printing},
volume = {37},
year = {2016}
}
@book{faucris.109848904,
abstract = {A remarkably regular organization of spirals converging to a focal point in control parameter space was recently predicted and then observed in a nonlinear circuit containing two diodes. Such spiral organizations are relatively hard to observe experimentally because they usually emerge very compressed. Here we show that a circuit with a tunnel diode displays not one but two large spiral cascades. We show such cascades to exist over wide parameter ranges and, therefore, we expect them to be easier to observe experimentally. © Springer-Verlag Berlin Heidelberg 2013.},
author = {Francke, Ricardo and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1007/978-3-642-34560-9-9},
faupublication = {yes},
isbn = {9783642345593},
pages = {161-177},
peerreviewed = {Yes},
title = {{Infinite} networks of hubs, spirals, and zig-zag patterns in self-sustained oscillations of a tunnel diode and of an erbium-doped fiber-ring laser},
volume = {459},
year = {2013}
}
@article{faucris.240531688,
abstract = {Understanding the mechanical behavior of powders used in additive manufacturing is a fundamental aspect to improve the quality and reliability of final parts. In this context, the role of particle shape for the powder bed quality is still not completely understood and sometimes overlooked. In this study, we propose a novel method to generate multisphere or clump representation from bi- or tridimensional templates of arbitrarily shaped particles. Particles from powders typically used in additive manufacturing, polyamide 11 (PA11) and polyamide 12 (PA12) are scanned (X-ray tomography) and used as prototypes for multisphere representation. Additionally, templates of modified PA11 particles (rounded through precipitation process) and SEM images of PA12 particles were used in multisphere reconstruction and further investigated. The multisphere representations retains not only most of the original template volume but also form factors associated with flowability characteristics – aspect ratio, flatness ratio, and elongation ratio. Using multisphere representations of the aforementioned powders, realistic discrete element method (DEM) simulations of the recoating step in additive manufacturing process are performed. The speed of the recoating mechanism follows realistic process velocities (100–250 mm/s). Packing density and roughness of powder beds are measured as a function of the recoating speed for different samples. Our results show that low aspect ratio (elongated) particles tend to form more compact layers of powders at lower recoating velocities. For higher recoating velocities, spherical particles perform better than elongated particles, due to better flowability characteristics. There is a clear dependency of recoating velocity and ideal particle shape for the deposition process, in contrast with the common assumption that spherical particles always perform better and should always be preferred.},
author = {Schiochet Nasato, Daniel and Pöschel, Thorsten},
doi = {10.1016/j.addma.2020.101421},
faupublication = {yes},
journal = {Additive Manufacturing},
keywords = {Discrete Element Method (DEM); Multisphere approach; Particle shape; Recoating},
note = {CRIS-Team Scopus Importer:2020-07-17},
peerreviewed = {Yes},
title = {{Influence} of particle shape in additive manufacturing: {Discrete} element simulations of polyamide 11 and polyamide 12},
volume = {36},
year = {2020}
}
@article{faucris.313776667,
abstract = {Efficient and non-invasive techniques of cargo delivery to biological cells are the focus of biomedical research because of their great potential importance for targeted drug therapy. Therefore, much effort is being made to study the characteristics of using nano-based biocompatible materials as systems that can facilitate this task while ensuring appropriate self-sealing of the cell membrane. Here, we study the effects of indentation and withdrawal of nanocone on phospholipid membrane by applying steered molecular dynamics (SMD) technique. Our results show that the withdrawal process directly depends on the initial position of the nanocone. The average force and work are considerably more significant in case of the withdrawal starting from a larger depth. This result is attributed to stronger hydrophobic interactions between the nanocone and lipid tails of the membrane molecules. Furthermore, when the indenter was started from the lower initial depth, the number of lipids removed from the membrane was several times smaller than the deeper indentation. The choice of the least invasive method for nanostructure-assisted drug delivery is crucial for possible applications in medicine. Therefore, the results presented in this work might be helpful in efficient and safe drug delivery with nanomaterials.},
author = {Raczyński, Przemysław and Górny, Krzysztof and Bełdowski, Piotr and Marciniak, Beata and Pöschel, Thorsten and Dendzik, Zbigniew},
doi = {10.1016/j.abb.2023.109802},
faupublication = {yes},
journal = {Archives of Biochemistry and Biophysics},
keywords = {Computer simulations; Molecular dynamics; Nanocone; Nanoindentation},
note = {CRIS-Team Scopus Importer:2023-11-10},
peerreviewed = {Yes},
title = {{Influence} of silicon nanocone on cell membrane self-sealing capabilities for targeted drug delivery—{Computer} simulation study},
volume = {749},
year = {2023}
}
@article{faucris.266113319,
abstract = {Improving the quality of the powder layers used in selective laser melting is a crucial step in bringing additive manufacturing to an industrial standard process. In this work, the effect of vibrations applied to the recoating mechanism (standard blade and roller) on the quality of the powder bed is evaluated. A numerical study using a realistic particle model of polyamide 12 is performed to evaluate the influence of frequency and amplitude in the porosity of the powder layer. Small frequency and amplitude, combined with small recoating velocity, lead to a reduction in the porosity of the granular bed. Large frequency and amplitude, however, lead to a vibro-fluidized state of the particles, loosening the granular bed and increasing the porosity. For practical applications, the choice of frequency and amplitude must be considered in combination with a specific translational velocity of the recoating mechanism.},
author = {Schiochet Nasato, Daniel and Briesen, Heiko and Pöschel, Thorsten},
doi = {10.1016/j.addma.2021.102248},
faupublication = {yes},
journal = {Additive Manufacturing},
keywords = {Discrete element method (DEM); Powder layer; Vibrating mechanism},
note = {CRIS-Team Scopus Importer:2021-11-12},
peerreviewed = {Yes},
title = {{Influence} of vibrating recoating mechanism for the deposition of powders in additive manufacturing: {Discrete} element simulations of polyamide 12},
volume = {48},
year = {2021}
}
@article{faucris.225166218,
abstract = {Smoothed particle hydrodynamics (SPH) has been widely applied to flows
with free surface, multi-phase flow, and systems with complex boundary
geometry. However, it has been shown that SPH suffers from transverse
instability when applied to simple wall-bounded shear flows such as
Poiseuille and Couette flows at moderate and high Reynolds number, Re≳1">Re >~ 1Re≳1">,
casting the application of SPH to practical situations into doubt,
where the Reynolds number is frequently large. Here, we consider
Poiseuille flows for a wide range of Reynolds number and find that the
documented instability of SPH can be avoided by using appropriate ratio
of smoothing length to particle spacing in combination with a density
re-initialization technique, which has not been systematically
investigated in simulations of simple shear flows. We also probe the
source of the instability and point out the limitations of SPH for
wall-bounded shear flows at high Reynolds numbe},
author = {Song, Baofang and Pazouki, Arman and Pöschel, Thorsten},
doi = {10.1016/j.camwa.2018.06.037},
faupublication = {yes},
journal = {Computers & Mathematics with Applications},
pages = {1447-1457},
peerreviewed = {Yes},
title = {{Instability} of smoothed particle hydrodynamics applied to {Poiseuille} flows},
url = {https://www.sciencedirect.com/science/article/pii/S0898122118303614},
volume = {76},
year = {2018}
}
@article{faucris.107292724,
abstract = {Weakly compressible smoothed particle hydrodynamics (WCSPH) has been widely applied to flows with free surfaces, multi-phase flow and systems with complex boundary geometry. It is known, however, that WCSPH suffers from transverse instability when applied to simple wall-bounded shear flows such as Poiseuille and Couette flows at moderate and high Reynolds number, Re & 1, casting the application of WCSPH to practical situations into doubt, where the Reynolds number is frequently large. Here, we consider Poiseuille flow for a wide range of Reynolds number and find that the instability of WCSPH can be avoided by using appropriate ratio of smoothing length to particle spacing in combination with a density re-initialization technique. We also probe the source of the instability and point out the limitations of WCSPH for wall-bounded shear flows at high Reynolds numbe},
author = {Song, Baofang and Pazouki, Arman and Pöschel, Thorsten},
faupublication = {yes},
journal = {Journal of Computational Physics},
peerreviewed = {Yes},
title = {{Instability} of {SPH} applied to {Poiseuille} flow},
year = {2015}
}
@article{faucris.261054156,
author = {Goychuk, Igor and Pöschel, Thorsten},
doi = {10.1038/s41567-021-01269-1},
faupublication = {yes},
journal = {Nature Physics},
note = {CRIS-Team Scopus Importer:2021-07-02},
peerreviewed = {Yes},
title = {{Insufficient} evidence for ageing in protein dynamics},
year = {2021}
}
@article{faucris.109947244,
abstract = {We investigate numerically the interaction of a stream of granular particles with a resting obstacle in two dimensions. For the case of high stream velocity we find that the force acting on the obstacle is proportional to the square of the stream velocity, the density and the obstacle size. This behaviour is equivalent to that of noninteracting hard spheres. For low stream velocity a gap between the obstacle and the incoming stream particles appears which is filled with granular gas of high temperature and low density. As soon as the gap appears the force does not depend on the square of velocity of the stream but the dependency obeys another law.},
author = {Buchholtz, Volkhard and Pöschel, Thorsten},
doi = {10.1007/PL00010908},
faupublication = {no},
journal = {Granular Matter},
pages = {33-41},
peerreviewed = {Yes},
title = {{Interaction} of a granular stream with an obstacle},
volume = {1},
year = {1998}
}
@article{faucris.228153748,
abstract = {Hyaluronic acid and phospholipids are two components that are present in the synovial fluid, and both are implicated as important facilitators of joint lubrication. In this work we aim to clarify how hyaluronic acid interacts with a phospholipid bilayer through their molecular interactions at the bilayer surface. To this end we performed molecular dynamics simulations of one hyaluronic acid molecule at a phospholipid bilayer in aqueous solution. The simulations were carried out for two aqueous solutions of equal concentrations, containing either NaCl or CaCl2. We analyzed hydrogen bonds, hydrophobic contacts and cation mediated bridges to clarify how hyaluoronic acid binds to a phospholipid bilayer. The analysis shows that calcium ions promote longer lasting bonds between the species as they create calcium ion bridges between the carboxylate group of hyaluronic acid and the phosphate group of the phospholipid. This type of additional bonding does not significantly influence the total number of contact created, but rather stabilizes the contact. The presented results can facilitate understanding of the role of hyaluronic acid and phospholipid interactions in terms of lubrication of articular cartilage.},
author = {Bełdowski, Piotr and Yuvan, Steven and Dėdinaitė, Andra and Claesson, Per M. and Pöschel, Thorsten},
doi = {10.1016/j.colsurfb.2019.110539},
faupublication = {yes},
journal = {Colloids and Surfaces B: Biointerfaces},
keywords = {Hyaluronic acid; Hydrogen bonds; Molecular dynamics simulations; Phospholipids},
note = {CRIS-Team Scopus Importer:2019-10-22},
peerreviewed = {Yes},
title = {{Interactions} of a short hyaluronan chain with a phospholipid membrane},
volume = {184},
year = {2019}
}
@article{faucris.109954064,
abstract = {A modified single-stage low pressure impactor is described to measure the coefficient of normal restitution e for nanoparticles. The device is analysed numerically using CFD, and the gas flow inside the structured impaction plate is studied. A formula for the calculation of e is derived and first measurements of e for spherical silver particles are presented together with numerical data obtained from force-based molecular dynamics simulations. Furthermore, the simulation data for e and the sticking probability are investigated in detail for the elastic, and partly for the plastic impaction regime. Particle collisions are of great importance for the modeling of fundamental processes in a wide range of interests. So far it was not possible to determine the coefficient of restitution for nanoparticles experimentally. Here, a new measurement technique is described. The results are compared to and extended by a numerical study for detailed analysis. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.},
author = {Schöner, Christian and Rennecke, Stephan and Weber, Alfred P. and Pöschel, Thorsten},
doi = {10.1002/cite.201300132},
faupublication = {yes},
journal = {Chemie Ingenieur Technik},
keywords = {Coefficient of restitution; Impaction; Molecular dynamics; Nanoparticle; Product design; Rebound},
pages = {365-374},
peerreviewed = {Yes},
title = {{Introduction} of a new technique to measure the coefficient of restitution for nanoparticles},
volume = {86},
year = {2014}
}
@article{faucris.109955164,
abstract = {About 20 years ago, Isaac Goldhirsch was one of the first to recognize that granular matter, behaving neither as a normal fluid nor as a normal solid, was not only an exotic terra
incognita for basic science, but is paradigmatic for a whole class of complex systems with irreversible interactions. This field became his passion at a time when he was already a
very successful, internationally renowned theoretical physicist. Certainly this helped to establish granular matter theory as a lively new branch of science. The very existence of a prominent new scientific journal ``Granular Matter'', entirely devoted to this field speaks for itself.},
author = {Pöschel, Thorsten and Wolf, Dietrich E.},
doi = {10.1007/s10035-012-0345-0},
faupublication = {yes},
journal = {Granular Matter},
peerreviewed = {Yes},
title = {{Isaac} {Goldhirsch}: a pioneer of granular matter theory},
year = {2012}
}
@article{faucris.106996164,
abstract = {Stochastic rotation dynamics (SRD) is a widely used method for the
mesoscopic modeling of complex fluids, such as colloidal suspensions or
multiphase flows. In this method, however, the underlying Cartesian grid
defining the coarse-grained interaction volumes induces anisotropy. We
propose an isotropic, lattice-free variant of stochastic rotation
dynamics, termed iSRD. Instead of Cartesian grid cells, we employ
randomly distributed spherical interaction volumes. This eliminates the
requirement of a grid shift, which is essential in standard SRD to
maintain Galilean invariance. We derive analytical expressions for the
viscosity and the diffusion coefficient in relation to the model
parameters, which show excellent agreement with the results obtained in
iSRD simulations. The proposed algorithm is particularly suitable to
model systems bound by walls of complex shape, where the domain cannot
be meshed uniformly. The presented approach is not limited to SRD but is
applicable to any other mesoscopic method, where particles interact
within certain coarse-grained volumes.},
author = {Mühlbauer, Sebastian and Strobl, Severin and Pöschel, Thorsten},
doi = {10.1103/PhysRevFluids.2.124204},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Isotropic} stochastic rotation dynamics},
volume = {2},
year = {2017}
}
@article{faucris.227883033,
abstract = {The underlying structure in apparently “randomly-packed” packed beds is a subject of topical interest, particularly in the context of deep processing, such as deep hydrodesulfurization. Packed beds typically exhibit “packing defects”; for instance, surface abnormalities such as a slope, a bump (convex surface), a hollow (concave surface), or even donut-shaped rings on the top surface of a packed bed. While these defects are observed at the top free surface of the packed bed, there are concerns that this may continue to propagate down the height, and in turn, cause local flow variations and differential wetting, which affect reactor performance, catalyst life, and formation of local hot spots. These defects come because of different protocols that are followed for packing particles, which are mainly developed out of empiricism since the physics of granular flow in confinements (such as a vertical cylindrical reactor vessel) is as yet not well understood. Earlier work on the structure of packed beds relates only to the spatial distribution of voidage, and not on how the particles are arranged with respect to each other in the reactor. This work is an attempt in that direction. We present first the use of Sequential Ballistic Deposition (SBD) algorithm to model the packing process itself, i.e., how the method of packing (modeled in this work through some simple protocols) yields a certain structure of the bed. Second, we show the use of Voronoi tessellation and the use of two of the Minkowski tensors (the Volume Moment Tensor and the Surface Orientation Tensor) to characterize the packed bed structure. Further analysis is presented which shows that we are able to fingerprint the packed bed formed through different packing methods, hence creating a link between the two.},
author = {Agrawal, Nikhil and Nair, Prapanch and Pöschel, Thorsten and Roy, Shantanu},
doi = {10.1016/j.cej.2018.08.206},
faupublication = {yes},
journal = {Chemical Engineering Journal},
keywords = {isotropy; Minkowski tensors; Sequential Ballistic Deposition; Trickle bed; Voidage distribution; Voronoi tessellation},
note = {CRIS-Team Scopus Importer:2019-10-15},
peerreviewed = {Yes},
title = {{Isotropy} of sphere packings in a cylindrical confinement},
volume = {377},
year = {2019}
}
@article{faucris.225767771,
abstract = {The Janssen model of stress redistribution within laterally bounded particulate assemblies is a longstanding and valuable theoretical framework, widely used in the design of industrial systems. However, the model relies on the assumption of a static packing of particles and has never been tested in a truly dynamic regime nor for a constraining system whose geometry is dynamically altered. In this paper, we explore the pressure distributions of granular beds housed within a container possessing a laterally mobile sidewall, allowing the depth, height, and cross-sectional areas of the systems studied to be dynamically altered, thus, inducing particle rearrangements and flow in the particulate system constrained thereby. We demonstrate that the systems studied can be successfully described by the Janssen model across a wide range of system expansion rates, including those for which liquidlike flow is clearly observed and propose an extension to the model allowing for an improved characterization of constrained dynamic systems.},
author = {Windows-Yule, C. R. K. and Mühlbauer, Sebastian and Torres Cisneros, Luis Armando and Nair, Prapanch and Marzulli, Valentina and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.100.022902},
faupublication = {yes},
journal = {Physical Review E},
note = {CRIS-Team WoS Importer:2019-09-06},
peerreviewed = {Yes},
title = {{Janssen} effect in dynamic particulate systems},
volume = {100},
year = {2019}
}
@article{faucris.122143824,
abstract = {We investigate the structure and adsorption of amphiphilic molecules at planar walls modified by tethered chain molecules using density functional theory. The molecules are modeled as spheres composed of a hydrophilic and hydrophobic part. The pinned chains are treated as tangentially jointed spheres that can interact with fluid molecules via orientation-dependent forces. Our density functional approach involves fundamental measure theory, thermodynamic perturbation theory for chains, and a mean-field approximation for describing the anisotropic interactions. We study the adsorption of the particles, focusing on the competition between the external field (due to the surface and due to attached chain molecules) and the interaction-induced ordering phenomena. © 2013 American Chemical Society.},
author = {Borówko, M. and Pöschel, Thorsten and Sokolowski, Stefan and Staszewski, T.},
doi = {10.1021/jp3105979},
faupublication = {yes},
journal = {Journal of Physical Chemistry B},
pages = {1166-1175},
peerreviewed = {Yes},
title = {{Janus} particles at walls modified with tethered chains},
volume = {117},
year = {2013}
}
@article{faucris.124192684,
abstract = {We study the kinetics of prion fibril growth, described by the nucleated polymerization model analytically and by means of numerical experiments. The elementary processes of prion fibril formation lead us to a set of differential equations for the number of fibrils, their total mass, and the number of prion monomers. In difference to previous studies we analyze this set by explicitly taking into account the time-dependence of the prion monomer concentration. The theoretical results agree with experimental data, whereas the generally accepted hypothesis of constant monomer concentration leads to a fibril growth behavior which is not in agreement with experiments. The obtained size distribution of the prion fibril aggregates is shifted significantly toward shorter lengths as compared to earlier results, which leads to a enhanced infectivity of the prion material. Finally, we study the effect of filtering of the inoculated material on the incubation time of the disease.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai and Frömmel, Cornelius},
doi = {10.1016/S0006-3495(03)74767-5},
faupublication = {no},
journal = {Biophysical Journal},
pages = {3460-3474},
peerreviewed = {Yes},
title = {{Kinetics} of {Prion} {Growth}},
url = {http://www.sciencedirect.com/science/article/pii/S0006349503747675},
volume = {85},
year = {2003}
}
@article{faucris.277822742,
abstract = {The dynamics of gases made of particles interacting dissipatively-known as granular gases-can be fully described by the translational and rotational motion of the individual particles; however, most of the results in the field refer to the limit of smooth particles, which implies that the rotational degrees of freedom are suppressed. Here we investigate the opposite limit: we consider a granular gas where the translational degrees of freedom are suppressed, and the key degrees of freedom are rotational. Our results indicate that for many-particle systems of pure rotators collective effects almost completely suppressed. This is in a sharp contrast to granular gases of smooth particles and other conventional matter where the translational degrees of freedom dominate the kinetics.},
author = {Torres Menendez, Harol and Altshuler, Ernesto and Brilliantov, Nikolai and Pöschel, Thorsten},
doi = {10.1088/1367-2630/ac78fb},
faupublication = {yes},
journal = {New Journal of Physics},
note = {CRIS-Team WoS Importer:2022-07-15},
peerreviewed = {Yes},
title = {{Lack} of collective motion in granular gases of rotators},
volume = {24},
year = {2022}
}
@article{faucris.109957584,
abstract = {The gravity-driven flow of granular material through a rough, narrow vertical pipe is described using the Langevin equation formalism. Above a critical particle density the homogeneous flow becomes unstable with respect to short-wave length perturbations. In correspondence with experimental observations, we find clogging and density waves in the flowing material.},
author = {Riethmüller, Tino and Schimansky-Geier, Lutz and Rosenkranz, Dirk and Pöschel, Thorsten},
doi = {10.1007/BF02180213},
faupublication = {no},
journal = {Journal of Statistical Physics},
keywords = {Flow of solids; Granular material; Stochastic processes},
pages = {421-430},
peerreviewed = {Yes},
title = {{Langevin} equation approach to granular flow in a narrow pipe},
volume = {86},
year = {1997}
}
@article{faucris.107384684,
abstract = {
Stochastic Rotation Dynamics (SRD) is a valuable numerical tool extensively used in many domains of hydrodynamics simulations including colloidal suspensions. We investigate the dynamics of two colloidal particles in the regime of low Reynolds number by means of SRD in 3D. In contrast to well-known analytical and experimental results, no long-range interaction between the suspended particles could be found, independent of the size of the particles and the Mach and Péclet numbers. We attribute this behavior to the compressible nature and low sound velocity in the SRD solvent. The inability of representing long-range interactions poses an important limitation to the applicability of SRD to certain physical systems. We provide an estimation of typical length scales for which SRD can be applied.
},
author = {Shakeri, Ali and Lee, Kuang-Wu and Pöschel, Thorsten},
doi = {10.1063/1.5008812},
faupublication = {yes},
journal = {Physics of Fluids},
month = {Jan},
peerreviewed = {unknown},
title = {{Limitation} of stochastic rotation dynamics to represent hydrodynamic interaction between colloidal particles},
volume = {30},
year = {2018}
}
@article{faucris.107691804,
abstract = {
Analogies between fluid flows and granular flows are useful because they pave the way for continuum treatments of granular media. However, in practice it is impossible to predict under what experimental conditions the dynamics of fluids and granulates are qualitatively similar. In the case of unsteadily driven systems no such analogy is known. For example, in a partially filled container subject to horizontal oscillations liquids slosh, whereas granular media of complex particles exhibit large-scale convection rolls. We here show that smooth monodisperse steel spheres exhibit liquidlike sloshing dynamics. Our findings highlight the role of particle material and geometry for the dynamics and phase transitions of the system.
},
author = {Avila Canellas, Kerstin and Steub, Laura and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.96.040901},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {unknown},
title = {{Liquidlike} sloshing dynamics of monodisperse granulate},
volume = {96},
year = {2017}
}
@inproceedings{faucris.307435633,
author = {Roy, Sudeshna and Xiao, Hongyi and Shaheen, Mohamad Yousef and Pöschel, Thorsten},
doi = {10.1007/978-3-031-32927-2\{\_}13},
faupublication = {yes},
peerreviewed = {Yes},
title = {{Local} {Structural} {Anisotropy} in {Particle} {Simulations} of {Powder} {Spreading} in {Additive} {Manufacturing}},
year = {2022}
}
@article{faucris.109959124,
abstract = {A gas of particles which collide inelastically if their impact velocity exceeds a certain value is investigated. In difference to common granular gases, cluster formation occurs only as a transient phenomenon. We calculate the decay of temperature due to inelastic collisions. In spite of the drastically reduced dissipation at low temperature the temperature surprisingly converges to zero. © 2003 Published by Elsevier Science B.V.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai and Schwager, Thomas},
doi = {10.1016/S0378-4371(03)00206-1},
faupublication = {no},
journal = {Physica A-Statistical Mechanics and Its Applications},
keywords = {Cluster formation; Granular gas; Molecular dynamics; Velocity dependent coefficient of restitution},
pages = {274-283},
peerreviewed = {Yes},
title = {{Long}-time behavior of granular gases with impact-velocity dependent coefficient of restitution},
url = {http://www.sciencedirect.com/science/article/pii/S0378437103002061},
volume = {325},
year = {2003}
}
@article{faucris.302890982,
abstract = {The entangled structure of polymeric materials is often described as resembling a bowl of spaghetti, swarms of earthworms, or snakes. These analogies not only illustrate the concept, but form the foundation of polymer physics. However, the similarity between these macroscopic, athermal systems and polymers in terms of topology remains uncertain. To better understand this relationship, we conducted an experiment using X-ray tomography to study the structure of arrays of linear rubber bands. We found that, similar to linear polymers, the average number of entanglements increases linearly with the length of the ribbons. Additionally, we observed that entanglements are less frequent near the surface of the container, where there are also more ends, similar to what has been seen in trapped polymers. These findings provide the first experimental evidence supporting the visualization of polymer structures using macroscopic, athermal analogues, confirming the initial intuitive insights of the pioneers of polymer physics.},
author = {Goemez, Leopoldo R. R. and Garciea, Nicolaes A. and Pöschel, Thorsten},
doi = {10.1039/d3sm00148b},
faupublication = {yes},
journal = {Soft Matter},
note = {CRIS-Team Scopus Importer:2023-05-26},
peerreviewed = {Yes},
title = {{Macroscopic} analogue to entangled polymers},
year = {2023}
}
@article{faucris.107686304,
abstract = {We create nearly perfect centimetric spheres of water by splitting a cavity consisting of two metal hemispheres coated with a hydrophobic paint and under-filled with liquid, while releasing the apparatus in free-fall. A high-speed camera captures how water spread on hydrophobic aluminum and polycarbonate plates perforated with cylindrical capillaries. We compare observations at the ZARM drop tower in Bremen with Lattice-Boltzmann numerical simulations of Frank, Perré and Li for the inertial phase of imbibition.},
author = {Steub, Laura and Kollmer, Jonathan and Paxson, Derek and Sack, Achim and Pöschel, Thorsten and Bartlett, John and Berman, Douglas and Richardson, Yaateh and Louge, Michel Y.},
doi = {10.1051/epjconf/201714016001},
faupublication = {yes},
journal = {EPJ Web of Conferences},
peerreviewed = {unknown},
title = {{Microgravity} spreading of water spheres on {Hydrophobic} capillary plates},
volume = {140},
year = {2017}
}
@article{faucris.225151595,
abstract = {In this study, the micromechanical interparticle contact behavior of “De NoArtri” (DNA-1A) grains is investigated, which is a lunar regolith simulant, using a custom-built micromechanical loading apparatus, and the results on the DNA-1A are compared with Ottawa sand which is a standard quartz soil. Material characterization is performed through several techniques. Based on microhardness intender and surface profiler analyses, it was found that the DNA-1A grains had lower values of hardness and higher values of surface roughness compared to Ottawa sand grains. In normal contact micromechanical tests, the results showed that the DNA-1A had softer behavior compared with Ottawa sand grains and that cumulative plastic displacements were observed for the DNA-1A simulant during cyclic compression, whereas for Ottawa sand grains elastic displacements were dominant in the cyclic sequences. In tangential contact micromechanical tests, it was shown that the interparticle friction values of DNA-1A were much greater than that of Ottawa sand grains, which was attributed to the softer contact response and greater roughness of the DNA-1A grains. Widely used theoretical models both in normal and tangential directions were fitted to the experimental data to obtain representative parameters, which can be useful as input in numerical analyses which use the discrete element method.},
author = {Sandeep, C. S. and Marzulli, Valentina and Cafaro, F. and Senetakis, K. and Pöschel, Thorsten},
doi = {10.1029/2019JB017589},
faupublication = {yes},
journal = {Journal of Geophysical Research. Solid Earth},
keywords = {interparticle friction; lunar regolith simulant; micromechanics; quartz sand},
note = {CRIS-Team Scopus Importer:2019-08-27},
pages = {8077-8100},
peerreviewed = {Yes},
title = {{Micromechanical} {Behavior} of {DNA}-{1A} {Lunar} {Regolith} {Simulant} in {Comparison} to {Ottawa} {Sand}},
volume = {124},
year = {2019}
}
@article{faucris.119755944,
author = {Wu, Chuan-Yu and Pöschel, Thorsten},
doi = {10.1007/s10035-013-0441-9},
faupublication = {yes},
journal = {Granular Matter},
pages = {389-390},
peerreviewed = {Yes},
title = {{Micro}-mechanics and dynamics of cohesive particle systems},
volume = {15},
year = {2013}
}
@article{faucris.269561076,
abstract = {When dense granular matter is sheared, the strain is often localized in
shear bands. After some initial transient these shear bands become
stationary. Here, we introduce a setup that periodically creates
horizontally aligned shear bands which then migrate upward through the
sample. Using x-ray radiography we demonstrate that this effect is
caused by dilatancy, the reduction in volume fraction occurring in
sheared dense granular media. Further on, we argue that these migrating
shear bands are responsible for the previously reported periodic
inflating and collapsing of the materia},
author = {Kollmer, Jonathan and Shreve, Tara and Claussen, Joelle and Gerth, Stefan and Salamon, Michael and Uhlmann, Norman and Schröter, Matthias and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.125.048001},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Migrating} {Shear} {Bands} in {Shaken} {Granular} {Matter}},
volume = {125},
year = {2020}
}
@article{faucris.239706041,
abstract = {A spinning gyroscope resists small torques in directions perpendicular to its axis, that is, the angular orientation of a body rigidly attached to a gyroscope is stable against rotation around certain axes. Since the angular orientation of a body is described by three angles (e.g., Euler angles), one might conclude that it is possible to stabilize the orientation of an object against rotation using a combination of three gyroscopes spinning around non-collinear axes. We perform experiments under conditions of weightlessness to demonstrate that systems of coupled gyroscopes cannot arrest the angular orientation of free-floating objects, in contradiction to a widespread myth about gyroscopic stabilization, based on the above arguments. (C) 2020 American Association of Physics Teachers.},
author = {Müller, Patric and Sack, Achim and Pöschel, Thorsten},
doi = {10.1119/10.0000517},
faupublication = {yes},
journal = {American Journal of Physics},
note = {CRIS-Team WoS Importer:2020-06-26},
pages = {175-181},
peerreviewed = {Yes},
title = {{Misconceptions} about gyroscopic stabilization},
volume = {88},
year = {2020}
}
@article{faucris.234633420,
abstract = {We study the mixing of rarefied gases in a T-shape micromixer by means of fully three-dimensional Monte-Carlo direct simulations. In contrast to previous 2D-results, the characteristics of the channel walls (thermal or specular) have significant effect on the mixing efficiency. For the 3D case, we characterize the mixing efficiency in dependence on temperature and mass density of the gases. Based on kinetic theory arguments, we develop a theoretical model in good agreement with the simulation results. In particular, the theoretical prediction of system size scaling agrees well with the simulation.},
author = {Hussain, Mubashir and Pöschel, Thorsten and Müller, Patric},
doi = {10.1016/j.applthermaleng.2018.09.090},
faupublication = {yes},
journal = {Applied Thermal Engineering},
keywords = {Discrete simulation Monte-Carlo; Mixing; Rarefied flows; Simulation; T-shape},
month = {Jan},
note = {CRIS-Team Scopus Importer:2020-02-21},
pages = {39-44},
peerreviewed = {Yes},
title = {{Mixing} of rarefied gases in {T}-shape micromixers},
volume = {146},
year = {2019}
}
@article{faucris.122771704,
abstract = {We propose a model for collisions between particles of a granular material and calculate the restitution coefficients for the normal and tangential motion as functions of the impact velocity from considerations of dissipative viscoelastic collisions. Existing models of impact with dissipation as well as the classical Hertz impact theory are included in the present model as special cases. We find that the type of collision (smooth, reflecting or sticky) is determined by the impact velocity and by the surface properties of the colliding grains. We observe a rather nontrivial dependence of the tangential restitution coefficient on the impact velocity.},
author = {Brilliantov, Nikolai and Spahn, Frank and Hertzsch, Jan-Martin and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.53.5382},
faupublication = {no},
journal = {Physical Review E},
pages = {5382-5392},
peerreviewed = {Yes},
title = {{Model} for collisions in granular gases},
volume = {53},
year = {1996}
}
@article{faucris.290028348,
abstract = {We introduce a surface tension model for Smoothed Particle Hydrodynamics (SPH) using a Young-Laplace pressure boundary condition. Our model does not rely on fitting parameters and can be applied to different variants of SPH. We demonstrate its robustness and accuracy by simulating several notoriously difficult three-dimensional free surface flow problems driven by surface tension.(c) 2023 Elsevier B.V. All rights reserved.},
author = {Blank, Michael and Nair, Prapanch and Pöschel, Thorsten},
doi = {10.1016/j.cma.2023.115907},
faupublication = {yes},
journal = {Computer Methods in Applied Mechanics and Engineering},
note = {CRIS-Team WoS Importer:2023-03-03},
peerreviewed = {Yes},
title = {{Modeling} surface tension in {Smoothed} {Particle} {Hydrodynamics} using {Young}-{Laplace} pressure boundary condition},
volume = {406},
year = {2023}
}
@article{faucris.109964404,
abstract = {We investigate autogenous fragmentation of dry granular material in rotating cylinders using two-dimensional molecular dynamics. By evaluation of spatial force distributions achieved numerically for various rotation velocities we argue that comminution occurs mainly due to the existence of these force chains. A statistical analysis of these force chains explains the spatial distribution of comminution efficiency in ball mills as measured experimentally by ROTHKEGEL and ROLF.},
author = {Buchholtz, V. and Freund, Jan A. and Pöschel, Thorsten},
doi = {10.1007/PL00011052},
faupublication = {no},
journal = {Bulk Solids Handling},
pages = {159-171},
peerreviewed = {Yes},
title = {{Molecular} dynamics of comminution in ball mills},
volume = {20},
year = {2000}
}
@article{faucris.109971664,
abstract = {We report the first three-dimensional molecular dynamics simulation of particle segregation by shaking. Two different containers are considered: one cylindrical and another with periodic boundary conditions. The dependence of the time evolution of a test particle inside the material is studied as a function of the shaking frequency and amplitude, damping coefficients, and dispersivity.},
author = {Gallas, Jason A. and Herrmann, Hans J. and Pöschel, Thorsten and Sokolowski, Stefan},
doi = {10.1007/BF02189239},
faupublication = {no},
journal = {Journal of Statistical Physics},
keywords = {Granular dynamics; Granular materials; Molecular dynamics; Size segregation; Whale effect},
pages = {443-450},
peerreviewed = {Yes},
title = {{Molecular} dynamics simulation of size segregation in three dimensions},
volume = {82},
year = {1996}
}
@article{faucris.122041524,
abstract = {Sand dunes are ubiquitous in deserts, on coasts, on the sea bottom, and on the surface of Mars, Venus and Titan. The quantitative understanding of dune dynamics is thus of relevance for a broad range of physical, geological and planetary sciences. A morphodynamic model for dunes, which combines an analytical description of the average turbulent wind field over the topography with a continuum saltation model, has proven successful to quantitatively reproduce the shape of aeolian dunes of different types. We present a short review on the physics of dune formation and the model development, as well as some future plans for further developments and applications.},
author = {Ribeiro Parteli, Eric Josef and Kroy, Klaus and Tsoar, Haim and Andrade, José S. and Pöschel, Thorsten},
doi = {10.1140/epjst/e2014-02263-2},
faupublication = {yes},
journal = {European Physical Journal - Special Topics},
pages = {2269-2283},
peerreviewed = {Yes},
title = {{Morphodynamic} modeling of aeolian dunes: {Review} and future plans},
volume = {223},
year = {2014}
}
@article{faucris.109973424,
abstract = {The response of an oscillating granular damper to an initial perturbation is studied using experiments performed in microgravity and granular dynamics simulations. High-speed video and image processing techniques are used to extract experimental data. An inelastic hard sphere model is developed to perform simulations and the results are in excellent agreement with the experiments. In line with previous work, a linear decay of the amplitude is observed. Although this behavior is typical for a friction-damped oscillator, through simulation it is shown that this effect is still present even when friction forces are absent. A simple expression is developed which predicts the optimal damping conditions for a given amplitude and is independent of the oscillation frequency and particle inelasticities. © 2011 American Physical Society.},
author = {Bannerman, Marcus and Kollmer, Jonathan and Sack, Achim and Heckel, Michael and Müller, Patric and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.84.011301},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Movers} and shakers: {Granular} damping in microgravity},
volume = {84},
year = {2011}
}
@article{faucris.217940857,
abstract = {We present an enhanced version of our previously engineered MyoRobot system for reliable, versatile and automated investigations of skeletal muscle or linear polymer material (bio)mechanics. That previous version already replaced strenuous manual protocols to characterize muscle biomechanics properties and offered automated data analysis. Here, the system was further improved for precise control over experimental temperature and muscle single fiber sarcomere length. Moreover, it also now features the calculation of fiber cross-sectional area via on-the-fly optical diameter measurements using custom-engineered microscope optics. With this optical systems integration, the MyoRobot 2.0 allows to tailor a wealth of recordings for relevant physiological parameters to be sequentially executed in living single myofibers. Research questions include assessing temperature-dependent performance of active or passive biomechanics, or automated control over length-tension or length-velocity relations. The automatically obtained passive stress-strain relationships and elasticity modules are important parameters in (bio)material science. From the plethora of possible applications, we validated the improved MyoRobot 2.0 by assessing temperature-dependent myofibrillar Ca
2+
sensitivity, passive axial compliance and Young's modulus. We report a Ca
2+
desensitization and a narrowed dynamic range at higher temperatures in murine M. extensor digitorum longus single fibers. In addition, an increased axial mechanical compliance in single muscle fibers with Young's moduli between 40 - 60 kPa was found, compatible with reported physiological ranges. These applications demonstrate the robustness of our MyoRobot 2.0 for facilitated single muscle fiber biomechanics assessment.},
author = {Haug, Michael and Meyer, Charlotte and Reischl, Barbara and Prölß, Gerhard and Nübler, Stefanie and Schürmann, Sebastian and Schneidereit, Dominik and Heckel, Michael and Pöschel, Thorsten and Rupitsch, Stefan and Friedrich, Oliver},
doi = {10.1016/j.bios.2019.04.052},
faupublication = {yes},
journal = {Biosensors and Bioelectronics},
keywords = {Axial compliance; Biomechatronics; Biosensor; Ca2+ sensitivity; EDL; MyoRobot; Sarcomere length; Single fiber; Skeletal muscle; Temperature control; Young's modulus},
note = {CRIS-Team Scopus Importer:2019-05-21},
peerreviewed = {Yes},
title = {{MyoRobot} 2.0: {An} advanced biomechatronics platform for automated, environmentally controlled skeletal muscle single fiber biomechanics assessment employing inbuilt real-time optical imaging},
volume = {138},
year = {2019}
}
@article{faucris.109976064,
abstract = {This paper shows that negative coefficients of normal restitution occur inevitably when the interaction force between colliding particles is finite. We derive an explicit criterion showing that for any set of material properties there is always a collision geometry leading to negative restitution coefficients. While from a phenomenological point of view, negative coefficients of normal restitution appear rather artificial, this phenomenon is generic and implies an important overlooked limitation of the widely used hard sphere model. The criterion is explicitly applied to two paradigmatic situations: for the linear dashpot model and for viscoelastic particles. In addition, we show that for frictional particles the phenomenon is less pronounced than for smooth spheres. © 2012 American Physical Society.},
author = {Müller, Patric and Krengel, Dominik and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.85.041306},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Negative} coefficient of normal restitution},
volume = {85},
year = {2012}
}
@incollection{faucris.218986563,
abstract = {The pioneers of the theory of classical kinetic equations are Rudolf Clausius (1822–1888), James Clerk Maxwell (1831–1879) and Ludwig Boltzmann (1844–1906). Their theories are based on the classical dynamics of particles in the phase space according to Liouville and on detailled studies of the classical mechanics of collisions between neutral molecules.},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3{\_}8},
faupublication = {yes},
isbn = {978-3-030-05734-3},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {233-266},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Non}-equilibrium: {Kinetic} equations},
volume = {953},
year = {2019}
}
@article{faucris.264297476,
abstract = {We investigate a basic model of nonlinear Brownian motion in a thermal environment, where nonlinear friction interpolates between viscous Stokes and dry Coulomb friction. We show that superdiffusion and supertransport emerge as a nonequilibrium critical phenomenon when such a Brownian motion is driven out of thermal equilibrium by a constant force. Precisely at the edge of a phase transition, velocity fluctuations diverge asymptotically and diffusion becomes superballistic. The autocorrelation function of velocity fluctuations in this nonergodic regime exhibits a striking aging behavior. },
author = {Goychuk, Igor and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.127.110601},
faupublication = {yes},
journal = {Physical Review Letters},
note = {CRIS-Team Scopus Importer:2021-09-24},
peerreviewed = {Yes},
title = {{Nonequilibrium} {Phase} {Transition} to {Anomalous} {Diffusion} and {Transport} in a {Basic} {Model} of {Nonlinear} {Brownian} {Motion}},
volume = {127},
year = {2021}
}
@incollection{faucris.218986811,
abstract = {With increasing density of plasmas, non-ideality effects become more and more apparent. This is of particular importance for plasmas with deep bound states, that is, when the thermal energy is smaller than or of the same order as the ground state energies of the atoms in the plasma. For hydrogen this is the case already for T < 10
5
K. Then, except for very low density, the convergence of the expansions becomes worse and we have to consider higher order terms. Sometimes even the transition to other expansion parameters, as the fugacity is recommended.},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3{\_}7},
faupublication = {yes},
isbn = {978-3-030-05734-3},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {211-231},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Non}-ideality and deep bound states in plasmas},
volume = {953},
year = {2019}
}
@article{faucris.109978484,
abstract = {We report a numerical investigation of the structural properties of very large three-dimensional heaps of particles produced by ballistic deposition from extended circular dropping areas. Very large heaps are found to contain three new geometrical characteristics not observed before: they may have two external angles of repose, an internal angle of repose, and four distinct packing fraction (density) regions. Such characteristics are shown to be directly correlated with the size of the dropping zone. In addition, we also describe how noise during the deposition affects the final heap structure. © 2012 American Physical Society.},
author = {Topic, Nikola and Gallas, Jason and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.109.128001},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Nonuniformities} in the angle of repose and packing fraction of large heaps of particles},
volume = {109},
year = {2012}
}
@inproceedings{faucris.109579404,
abstract = {Part of the optimization steps for additive manufacturing is related to the correct understanding of the mechanical behavior of the powder used in the process. Obtain this understanding based purely on experiments might be a difficult and sometimes prohibitive task. A particle-based numerical tool can provide critical information for correct understanding of powder deposition process. Numerical simulations through the Discrete Element Method (DEM) provide a useful mean to investigate the additive manufacturing process, given the possibility to study particle-scale information that are difficult to access experimentally. The characteristics of the recoated powder bed are investigated in the packed bed region and onto the manufactured part using PA12 commercial powder. Particle size distribution, contact and non-contact cohesive forces are incorporated in the numerical model. Furthermore, the non-spherical shape of real particles is taken explicitly into account in numerical simulations. A blade-type recoating system is used to form the powder bed and its roughness is calculated. Experimental measurements are performed by fringe projection. Several areas of the recoated powder layers can be scanned with this optical measurement method. Thus, the analyzed surface roughness can be compared with the simulated quantities to validate the numerical model. The sintered part is modelled as a prescribed rigid static region in the simulated system. The powder recoated in the sintered region may have different characteristics (packing, roughness) compared to the powder bed region. Recoating process is modelled using two different shapes for the sintered region. The amount of material recoated and the surface roughness are then calculated for the powder bed as well as for the sintered regi},
author = {Schiochet Nasato, Daniel and Heinl, Martin and Hausotte, Tino and Pöschel, Thorsten},
booktitle = {PARTICLES},
date = {2017-09-26/2017-09-28},
editor = {V International Conference on Particle-based Methods – Fundamentals and Applications},
faupublication = {yes},
keywords = {Granular Materials; DEM; Additive Manufacturing; Surface Roughness; Numerical simulation},
pages = {429-439},
peerreviewed = {unknown},
title = {{Numerical} and experimental study of the powder bed characteristics in the recoated bed of the additive manufacturing process},
venue = {Hannover},
year = {2017}
}
@article{faucris.119756164,
abstract = {The evolution of a pile of granular material is investigated by molecular dynamics using a new model including nonsphericity of the particles instead of introducing static friction terms. The angle of repose of the piles as well as the avalanche statistics gathered by the simulation agree with experimental results. The angle of repose of the pile is determined by the shape of the grains. Our results are compared with simulations using spherical grains and static friction. © 1994.},
author = {Buchholtz, Volkhard and Pöschel, Thorsten},
doi = {10.1016/0378-4371(94)90467-7},
faupublication = {no},
journal = {Physica A-Statistical Mechanics and Its Applications},
pages = {390-401},
peerreviewed = {Yes},
title = {{Numerical} investigations of the evolution of sandpiles},
volume = {202},
year = {1994}
}
@article{faucris.109852864,
abstract = {Transverse dunes, which form under unidirectional winds and have fixed profile in the direction perpendicular to the wind, occur on all celestial objects of our solar system where dunes have been detected. Here we perform a numerical study of the average turbulent wind flow over a transverse dune by means of computational fluid dynamics simulations. We find that the length of the zone of recirculating flow at the dune lee-the separation bubble-displays a surprisingly strong dependence on the wind shear velocity, u *: it is nearly independent of u * for shear velocities within the range between 0.2â€...m/s and 0.8â€...m/s but increases linearly with u * for larger shear velocities. Our calculations show that transport in the direction opposite to dune migration within the separation bubble can be sustained if u * is larger than approximately 0.39â€...m/s, whereas a larger value of u * (about 0.49â€...m/s) is required to initiate this reverse transport.},
author = {Araújo, Ascânio D. and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten and Andrade, José S. and Herrmann, Hans J.},
doi = {10.1038/srep02858},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Numerical} modeling of the wind flow over a transverse dune},
volume = {3},
year = {2013}
}
@inproceedings{faucris.116693324,
abstract = {Numerical simulations by means of the Discrete Element Method (DEM) can provide a helpful tool in the investigation of the packing behavior of powders. In this type of numerical simulations, the Newton’s equations of motion for every single particle in the system are solved by taking into account all forces and torques acting on it, both due to external fields and due to interactions with other particles in the system},
author = {Blümel, Christina and Ribeiro Parteli, Eric Josef and Schmidt, Jochen and Wirth, Karl Ernst and Peukert, Wolfgang and Pöschel, Thorsten},
booktitle = {85th Annual Meeting of the International Association of Applied Mathematics and Mechanics – GAMM 2014},
date = {2014-03-10/2014-03-14},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Numerical} study of the packing density of fine powders by means of the {Discrete} {Element} {Method}},
year = {2014}
}
@article{faucris.116698384,
author = {Behringer, Robert and Jenkins, James and Miloh, Touvia and Orszag, Steven and Pöschel, Thorsten and Rosenau, Philip and Savage, Stuart and Schuss, Zeev and Shemer, Lev},
faupublication = {yes},
journal = {Journal of Fluid Mechanics},
pages = {1 - 2},
peerreviewed = {Yes},
title = {{Obituary}: {PROFESSOR} {ISAAC} {GOLDHIRSCH} 11 {October} 1949–29 {April} 2010},
volume = {655},
year = {2010}
}
@article{faucris.109981564,
abstract = {When granular systems are modeled by hard spheres, particle-particle collisions are considered as instantaneous events. This implies that while the velocities change according to the collision rule, the positions of the particles are the same before and after such an event. We show that depending on the material and system parameters, this assumption may fail. For the case of viscoelastic particles we present a universal condition which allows to assess whether hard-spheremodeling and, thus, event-driven Molecular Dynamics simulations are justified. © Springer-Verlag 2012.},
author = {Müller, Patric and Pöschel, Thorsten},
doi = {10.1007/s10035-012-0324-5},
faupublication = {yes},
journal = {Granular Matter},
keywords = {Coefficient of normal restitution; Event-driven molecular dynamics; Granular gases; Hard sphere model; Viscoelastic spheres},
pages = {115-120},
peerreviewed = {Yes},
title = {{Oblique} impact of frictionless spheres: {On} the limitations of hard sphere models for granular dynamics},
volume = {14},
year = {2012}
}
@article{faucris.106954804,
abstract = {Background: For many applications one wishes to decide whether a certain set of numbers originates from an equiprobability distribution or whether they are unequally distributed. Distributions of relative frequencies may deviate significantly from the corresponding probability distributions due to finite sample effects. Hence, it is not trivial to discriminate between an equiprobability distribution and non-equally distributed probabilities when knowing only frequencies. Results: Based on analytical results we provide a software tool which allows to decide whether data correspond to an equiprobability distribution. The tool is available at http://bioinf.charite.de/ equifreq/. Conclusions: Its application is demonstrated for the distribution of point mutations in coding genes. © 2003 Pöschel et al; licensee BioMed Central Ltd.},
author = {Pöschel, Thorsten and Frömmel, Cornelius and Gille, Christoph},
doi = {10.1186/1471-2105-4-58},
faupublication = {no},
journal = {BMC Bioinformatics},
peerreviewed = {Yes},
title = {{Online} tool for the discrimination of equi-distributions},
url = {http://www.biomedcentral.com/1471-2105/4/58},
volume = {4},
year = {2003}
}
@article{faucris.123556444,
abstract = {Convection, surface fluidization, spontaneous heap formation, and other effects are analyzed when a granular material is shaken vertically. The existence of a threshold for the Froude number Γ = Aω-0$//g is investigated, below which these effects cannot be observed. It is proved that there is no such threshold using computer simulation.},
author = {Pöschel, Thorsten and Schwager, Thomas and Salueña, Clara},
doi = {10.1103/PhysRevE.62.1361},
faupublication = {no},
journal = {Physical Review E},
pages = {1361-1367},
peerreviewed = {Yes},
title = {{Onset} of fluidization in vertically shaken granular material},
volume = {62},
year = {2000}
}
@article{faucris.107287004,
abstract = {
The mechanical properties of nano particles cannot be reliably described by bulk material characteristics due to their atomic structure, leading to pronounced anisotropic behavior. By means of Molecular Dynamics simulations, we study the impact of 5 nm Ag-particles on an adhesive, rigid wall. We show that the main characteristics of the impact such as the coecient of normal restitution, the sticking probability, the maximal contact force, and the degree of plastic deformation of the particle depend sensitively on the angular orientation of the nano particle prior to the impact. We introduce the scalar parameter ω describing the orientation and show that the impact characteristics can be described as functions of ω.
},
author = {Schöner, Christian and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.98.022902},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Orientation} dependent properties of nanoparticle impact},
volume = {98},
year = {2018}
}
@article{faucris.107702144,
abstract = {When a thin tube is dipped into water, the water will ascend to a certain height, against the action of gravity. While this effect, termed capillarity, is well known, recent experiments have shown that agitated granular matter reveals a similar behavior. Namely, when a vertical tube is inserted into a container filled with granular material and is then set into vertical vibration, the particles rise up along the tube. In the present Letter, we investigate the effect of granular capillarity by means of numerical simulations and show that the effect is caused by convection of the granular material in the container. Moreover, we identify two regimes of behavior for the capillary height Hc∞ depending on the tube-to-particle-diameter ratio, D/d. For large D/d, a scaling of Hc∞ with the inverse of the tube diameter, which is reminiscent of liquids, is observed. However, when D/d decreases down to values smaller than a few particle sizes, a uniquely granular behavior is observed where Hc∞ increases linearly with the tube diameter.},
author = {Fan, Fengxian and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.118.218001},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {unknown},
title = {{Origin} of {Granular} {Capillarity} {Revealed} by {Particle}-{Based} {Simulations}},
volume = {118},
year = {2017}
}
@article{faucris.119740984,
abstract = {Barchan dunes - crescent-shaped dunes that form in areas of unidirectional winds and low sand availability - commonly display an asymmetric shape, with one limb extended downwind. Several factors have been identified as potential causes for barchan dune asymmetry on Earth and Mars: asymmetric bimodal wind regime, topography, influx asymmetry and dune collision. However, the dynamics and potential range of barchan morphologies emerging under each specific scenario that leads to dune asymmetry are far from being understood. In the present work, we use dune modeling in order to investigate the formation and evolution of asymmetric barchans. We find that a bimodal wind regime causes limb extension when the divergence angle between primary and secondary winds is larger than 90°, whereas the extended limb evolves into a seif dune if the ratio between secondary and primary transport rates is larger than 25%. Calculations of dune formation on an inclined surface under constant wind direction also lead to barchan asymmetry, however no seif dune is obtained from surface tilting alone. Asymmetric barchans migrating along a tilted surface move laterally, with transverse migration velocity proportional to the slope of the terrain. Limb elongation induced by topography can occur when a barchan crosses a topographic rise. Furthermore, transient asymmetric barchan shapes with extended limb also emerge during collisions between dunes or due to an asymmetric influx. Our findings can be useful for making quantitative inference on local wind regimes or spatial heterogeneities in transport conditions of planetary dune fields hosting asymmetric barchans. © 2013 Elsevier B.V.},
author = {Ribeiro Parteli, Eric Josef and Durán, Orencio and Bourke, Mary C. and Tsoar, Haim and Pöschel, Thorsten and Herrmann, Hans J.},
doi = {10.1016/j.aeolia.2013.12.002},
faupublication = {yes},
journal = {Aeolian Research},
keywords = {Barchan dunes; Dune asymmetry; Dune model; Sand transport; Wind erosion},
pages = {121-133},
peerreviewed = {Yes},
title = {{Origins} of barchan dune asymmetry: {Insights} from numerical simulations},
volume = {12},
year = {2014}
}
@article{faucris.237700619,
abstract = {The quantitative description of packing behaviour of particulate systems under consideration of realistic particle size distributions and material properties poses one challenging problem in powder technology, with impacts on a broad range of technological areas. Here we investigate the packing characteristics of micrometer to millimeter-sized, polydisperse spherical particle systems of glass, zirconia and copper by means of experimental measurements of the bulk density, X-ray microtomography (CT) and numerical simulations of the granular packings using a 3d discrete element method (DEM). The applied DEM method takes realistic material properties into account and considers the experimentally obtained particle size distributions as well as attractive inter-particle forces including adhesion (Johnson, Kendall, Roberts (JKR)) and non-bonded van der Waals (vdW) interactions. Good agreement of the packing densities predicted by DEM and observed in the experiments (bulk density determination & CT) is found. Moreover, we show that a simple mathematical expression for the packing fraction as a function of average particle size of the polydisperse powder system describes well our experimental and simulation results for all investigated materials, with only two fitting parameters. From the DEM simulations, the mean (first) coordination number in the respective polydisperse packing is extracted and discussed with respect to the experimentally obtained direct neighborhood detection from X-ray tomography and in context of previous works. The mean coordination number shows a rather broad variance due to the polydispersity of the samples considered. It also shows a remarkable dependency on the definition of particle contact. Therefore, caution is advised when evaluating coordination numbers with this quantity being highly dependent on the instrumental resolution.},
author = {Schmidt, Jochen and Parteli, Eric J.R. and Uhlmann, Norman and Wörlein, Norbert and Wirth, Karl-Ernst and Pöschel, Thorsten and Peukert, Wolfgang},
doi = {10.1016/j.apt.2020.03.018},
faupublication = {yes},
journal = {Advanced Powder Technology},
keywords = {Bulk density; Discrete element method; Packings; X-ray microtomography},
note = {CRIS-Team Scopus Importer:2020-04-24},
peerreviewed = {Yes},
title = {{Packings} of micron-sized spherical particles – {Insights} from bulk density determination, {X}-ray microtomography and discrete element simulations},
year = {2020}
}
@article{faucris.235073172,
abstract = {Unraveling the packing structure of dense assemblies of semiflexible rings is not only fundamental for the dynamical description of polymer rings, but also key to understand biopackaging, such as observed in circular DNA of viruses or genome folding. Here we use X-ray tomography to study the geometrical and topological features of disordered packings of rubber bands in a cylindrical container. Assemblies of short bands assume a liquid-like disordered structure, with short-range orientational order, and reveal only minor influence of the container. In the case of longer bands, the confinement causes folded configurations and the bands interpenetrate and entangle. Most of the systems are found to display a threading network which percolates the system. Surprisingly, for long bands whose diameter is more than twice the diameter of the container, we found that all bands interpenetrate each other, in a complex fully entangled structure.},
author = {Gómez, Leopoldo R. and García, Nicolás A. and Pöschel, Thorsten},
doi = {10.1073/pnas.1914268117},
faupublication = {yes},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
keywords = {Entanglements; Filamentous matter; Geometry; Topology; X-ray tomography},
note = {CRIS-Team Scopus Importer:2020-02-28},
pages = {3382-3387},
peerreviewed = {Yes},
title = {{Packing} structure of semiflexible rings},
volume = {117},
year = {2020}
}
@article{faucris.113989744,
abstract = {The development of reliable strategies to optimize part production in additive manufacturing technologies hinges, to a large extent, on the quantitative understanding of the mechanical behavior of the powder particles during the application process. Since it is difficult to acquire this understanding based on experiments alone, a particle-based numerical tool for the simulation of powder application is required. In the present work, we develop such a numerical tool and apply it to investigate the characteristics of the powder layer deposited onto the part using a roller as the coating system. In our simulations, the complex geometric shapes of the powder particles are taken explicitly into account. Our results show that increasing the coating speed leads to an increase in the surface roughness of the powder bed, which is known to affect part quality. We also find that, surprisingly, powders with broader size distributions may lead to larger values of surface roughness as the smallest particles are most prone to form large agglomerates thus increasing the packing's porosity. Moreover, we find that the load on the part may vary over an order of magnitude during the coating process owing to the strong inhomogeneity of inter-particle forces in the granular packing. Our numerical tool can be used to assist - and partially replace - experimental investigations of the flowability and packing behavior of different powder systems as a function of material and process parameters.},
author = {Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1016/j.powtec.2015.10.035},
faupublication = {yes},
journal = {Powder Technology},
keywords = {Additive manufacturing; Discrete element method; Numerical simulation},
pages = {96-102},
peerreviewed = {Yes},
title = {{Particle}-based simulation of powder application in additive manufacturing},
volume = {288},
year = {2016}
}
@article{faucris.119402404,
abstract = {
The development of reliable strategies to optimize part production in additive manufacturing technologies hinges, to a large extent, on the quantitative understanding of the mechanical behavior of the powder particles during the application process. Since it is difficult to acquire this understanding based on experiments alone, a particle- based numerical tool for the simulation of powder application is required. In the present work, we develop such a numerical tool and apply it to investigate the characteristics of the powder layer de posited onto the part using a roller as the coating system. In our simulations, the complex geometric shapes of the powder particles are taken explicitly into account. Our results show that increasing the coating speed leads to an increase in the surface roughness of the powder bed, which is known to affect part quality. We also find that, surprisingly, powders with broader size distributions may lead to larger values of surface roughness as the smallest particles are most prone to form large agglomerates thus increasing the packing’s porosity. Moreover, we find that the load on the part may vary over an order of magnitude during the coating process owing to the strong inhomogeneity of inter-particle forces in the granular packing. Our numerical tool can be used to assist — and partially replace — experimental investigations of the flowability and packing behavior of different powder systems as a function of material and process parameters.
},
author = {Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1051/epjconf/201714015013},
faupublication = {yes},
journal = {EPJ Web of Conferences},
peerreviewed = {unknown},
title = {{Particle}-based simulations of powder coating in additive manufacturing suggest increase in powder bed roughness with coating speed},
volume = {140},
year = {2017}
}
@inproceedings{faucris.113993484,
abstract = {Fluidized beds with secondary gas injection enjoy great popularity in process industry. Owing to their characteristic properties such as intense mixing of solids, excellent mass and heat transfer conditions as well as easy handling of solids, this type of apparatus is applied in various fields of process engineering nowadays. In the past decades research concerning fluidized beds with secondary gas injection has focused on understanding how solid particles and the injected gas are distributed within the apparatus. With the aid of invasive measurement techniques the region surrounding the injector nozzle was investigated with respect to the penetration depth of the gas jet above the nozzle orifice as well as the jet opening angle. A major drawback of the previously used measurement techniques consists in their invasive nature. Penetration of the injection zone by a probe can severely influence the local flow pattern and consequently has a detrimental effect on the reliability of the measured data. Therefore in the presented work for the first time the solids distribution as well as the motion of a single particle in a fluidized bed with secondary gas injection has been investigated by positron emission particle tracking (PEPT). This non-invasive technique is based on labeling one single particle, randomly selected from the bulk, radioactively, which allows for tracking its motion with high temporal and spatial resolution. The obtained data are compared with results derived from invasive measurements. Moreover PEPT-data have been used to perform investigations on the residence time behavior of particles within the jet region and the suspended phase. It could be found that the combination of invasive measurements and PEPT provide valuable information for the design and optimization of fluidized bed reactors with a well-defined injection zone.},
author = {Hensler, Timo and Tupy, Martin and Strer, Timo and Pöschel, Thorsten and Wirth, Karl-Ernst},
booktitle = {7th World Congress on Particle Technology, WCPT 2014},
doi = {10.1016/j.proeng.2015.01.204},
faupublication = {yes},
keywords = {Fluidized bed; positron emission particle tracking; residence time behavior; secondary gas injection; solids distribution},
pages = {850-857},
peerreviewed = {Yes},
publisher = {Elsevier Ltd},
title = {{Particle} tracking in fluidized beds with secondary gas injection},
volume = {102},
year = {2015}
}
@article{faucris.212766115,
abstract = {Fluidized beds with secondary gas injection enjoy great popularity in process industry. Owing to their characteristic properties such as intense mixing of solids, excellent mass and heat transfer conditions as well as easy handling of solids, this type of apparatus is applied in various fields of process engineering nowadays. In the past decades research concerning fluidized beds with secondary gas injection has focused on understanding how solid particles and the injected gas are distributed within the apparatus. With the aid of invasive measurement techniques the region surrounding the injector nozzle was investigated with respect to the penetration depth of the gas jet above the nozzle orifice as well as the jet opening angle. A major drawback of the previously used measurement techniques consists in their invasive nature. Penetration of the injection zone by a probe can severely influence the local flow pattern and consequently has a detrimental effect on the reliability of the measured data. Therefore in the presented work for the first time the solids distribution as well as the motion of a single particle in a fluidized bed with secondary gas injection has been investigated by positron emission particle tracking (PEPT). This non-invasive technique is based on labeling one single particle, randomly selected from the bulk, radioactively, which allows for tracking its motion with high temporal and spatial resolution. The obtained data are compared with results derived from invasive measurements. Moreover PEPT-data have been used to perform investigations on the residence time behavior of particles within the jet region and the suspended phase. It could be found that the combination of invasive measurements and PEPT provide valuable information for the design and optimization of fluidized bed reactors with a well-defined injection zone.},
author = {Hensler, Timo and Tupy, Martin and Strer, Timo and Pöschel, Thorsten and Wirth, Karl-Ernst},
doi = {10.1016/j.proeng.2015.01.204},
faupublication = {yes},
journal = {Procedia Engineering},
note = {EAM Import::2019-03-08},
pages = {850-857},
peerreviewed = {unknown},
title = {{Particle} {Tracking} in {Fluidized} {Beds} with {Secondary} {Gas} {Injection}},
volume = {102},
year = {2015}
}
@article{faucris.109987504,
abstract = {We study the mechanism leading to the formation of stripe-like patterns in a rectangular container filled with a sub-monolayer of frictional spherical particles when it is subjected to horizontal oscillations. By means of Molecular Dynamics simulations we could reproduce the experimental results. Systematic simulations allow to identify friction to be responsible for the pattern formation, that is, the tangential interaction between contacting particles and between the particles and the floor of the container. When particles are in contact with the floor and other adjacent particles simultaneously, there emerges a frustrated situation in which the particles are prevented from rolling on the floor. This effect leads to local jamming and eventually to stripe-like pattern formation. In the long time evolution, the stripes are unstable. Stripes may merge as well as disintegrate. © 2013 Springer-Verlag Berlin Heidelberg.},
author = {Krengel, Dominik and Strobl, Severin and Sack, Achim and Heckel, Michael and Pöschel, Thorsten},
doi = {10.1007/s10035-013-0411-2},
faupublication = {yes},
journal = {Granular Matter},
keywords = {Frustration effects; Horizontal shaking; Pattern formation},
pages = {377-387},
peerreviewed = {Yes},
title = {{Pattern} formation in a horizontally shaken granular submonolayer},
volume = {15},
year = {2013}
}
@article{faucris.109988384,
abstract = {We investigate the transport of proteins inside the proteasome and propose an active-transport mechanism based on a spatially asymmetric interaction potential of peptide chains. The transport is driven by fluctuations which are always present in such systems. We compute the peptide-size-dependent transport rate which is essential for the functioning of the proteasome. In agreement with recent experiments, varying temperature changes the transport mechanism qualitatively. © EDP Sciences.},
author = {Zaikin, A. and Pöschel, Thorsten},
doi = {10.1209/epl/i2004-10426-8},
faupublication = {no},
journal = {EPL - Europhysics Letters},
pages = {725-731},
peerreviewed = {Yes},
title = {{Peptide}-size-dependent active transport in the proteasome},
volume = {69},
year = {2005}
}
@article{faucris.215447040,
abstract = {An impressive ping-pong ball cannon can be made by placing a bottle of liquid nitrogen at the bottom of a container and quickly covering it with, say, 1500 ping-pong balls. The liquid turns rapidly into a gas whose mounting pressure explodes the bottle, sending a swarm of balls upward out of the container. Surprisingly, the container also moves upward. This is a counterintuitive effect because the balance of forces, that is, Newton's third law does not seem to allow the container to move upwards. We explain the effect as a consequence of granular jamming in combination with Coulomb's friction law. (C) 2019 American Association of Physics Teachers.},
author = {Pöschel, Thorsten and Nasato, Daniel S. and Parteli, Eric J. R. and Gallas, Jason and Müller, Patric},
doi = {10.1119/1.5088805},
faupublication = {yes},
journal = {American Journal of Physics},
note = {CRIS-Team WoS Importer:2019-04-04},
pages = {255-263},
peerreviewed = {Yes},
title = {{Ping}-pong ball cannon: {Why} do barrel and balls fly in the same direction?},
volume = {87},
year = {2019}
}
@article{faucris.110308924,
abstract = {We investigate jammed granular matter in a slowly rotating drum partially filled with granular material and find a state of polydirectional stability. In this state, the material responds elastically to small stresses in a wide angular interval while it responds by plastic deformation when subjected to small stresses outside this interval of directions. We describe the evolution of the granulate by means of a rate equation and find quantitative agreement with the experiment. The state of polydirectional stability complements the fragile state, where the material responds elastically to small applied stresses only in a certain direction but even very small stresses in any other direction would lead to plastic deformations. Similar to fragile matter, polydirectionally stable matter is created in a dynamic process by self-organization. © 2013 American Physical Society.},
author = {Zimber, Fabian and Kollmer, Jonathan and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.111.168003},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Polydirectional} stability of granular matter},
volume = {111},
year = {2013}
}
@article{faucris.118441224,
abstract = {We apply positron emission particle tracking (PEPT) to a gas-solid fluidized bed with injection of a secondary gas through a centrally arranged nozzle and present a method to compute stationary fluid-dynamic characteristics of the system from the trajectories of a test particle. In order to evaluate this non-invasive method we compare the field of density obtained by PEPT with the density obtained by a traditional, well-established and approved, yet invasive, measurement technique to find good agreement. Besides the penetration depth of the jet region and the opening angle of the jet which are inferred from the density field, we use PEPT to measure quantities whose measurement using traditional methods is rather sophisticated, including the residence time of particles in the jet region and the suspended phase, the coefficients of axial and radial dispersion and the material flux across the jet boundaries. We conclude that PEPT is a reliable and at the same time versatile technique to measure stationary fluid-dynamic properties of dynamical particle systems at spatial resolution only limited by the duration of the measurement.},
author = {Hensler, Timo and Tupy, Martin and Strer, Timo and Pöschel, Thorsten and Wirth, Karl-Ernst},
doi = {10.1016/j.powtec.2015.04.005},
faupublication = {yes},
journal = {Powder Technology},
keywords = {Dispersion coefficient; Fluidized bed; Measurement technology; Positron emission particle tracking; Residence time; Secondary gas injection},
pages = {113-122},
peerreviewed = {Yes},
title = {{Positron} emission particle tracking in fluidized beds with secondary gas injection},
volume = {279},
year = {2015}
}
@article{faucris.122146024,
author = {Masel, Joanna and Jansen, Vincent A. A. and Pöschel, Thorsten and Brilliantov, Nikolai V. and Frömmel, Cornelius},
doi = {10.1529/biophysj.104.039867},
faupublication = {no},
journal = {Biophysical Journal},
pages = {728-729},
peerreviewed = {Yes},
title = {{Prion} {Kinetics} (multiple letters)},
volume = {87},
year = {2004}
}
@article{faucris.122138764,
abstract = {We consider the attenuation of the oscillation of a flat spring due to the action of a granular damper. The efficiency of the damper is quantified by evaluating the position of the oscillator as a function of time using a Hall effect based position sensor. Performing experiments for a large abundance of parameters under conditions of microgravity, we confirm a recent theory for granular damping (Kollmer et al. in New J Phys 15:093023, 2013) and show that the theory remains approximately valid even beyond the limits of its derivation.},
author = {Sack, Achim and Heckel, Michael and Kollmer, Jonathan and Pöschel, Thorsten},
doi = {10.1007/s10035-014-0539-8},
faupublication = {yes},
journal = {Granular Matter},
keywords = {Dissipation; Granular systems; Vibration damping},
pages = {73-82},
peerreviewed = {Yes},
title = {{Probing} the validity of an effective-one-particle description of granular dampers in microgravity},
volume = {17},
year = {2014}
}
@incollection{faucris.218985571,
abstract = {The development of a systematic statistical theory for systems with Coulomb interactions is related to characteristic problems: 1.Debye’s screening problem, 2.Wigner’s problem of lattice formation,3.Herzfeld’s bound state problem.},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3{\_}6},
faupublication = {yes},
isbn = {978-3-030-05734-3},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {171-210},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Quantum} statistics of dilute plasmas},
volume = {953},
year = {2019}
}
@article{faucris.106293044,
abstract = {Systems of granular rotors (Vibrots), that is, small devices that convert linear
vibrational motion into rotation by frictional impact, are of scientific interest
since they could reveal various types of collective behavior. Looking at an
isolated Vibrot, we note at least two dierent dynamical modes, depending on the
parameters of the vibrational driving. By means of Finite Element simulations,
we reveal the driving mechanism for both cases which may be correspondingly
identified as ratcheting and tumbling. The transition between both modes
resembles period doubling in certain bouncing ball problems leading eventually
to chaotic motion in such systems.},
author = {Scholz, Christian and Dsilva, Sean and Pöschel, Thorsten},
doi = {10.1088/1367-2630/18/12/123001},
faupublication = {yes},
journal = {New Journal of Physics},
peerreviewed = {Yes},
title = {{Ratcheting} and tumbling motion of {Vibrots}},
volume = {18},
year = {2016}
}
@incollection{faucris.218985819,
abstract = {From the classical kinetic theory of gases we know the equation of state of the ideal gas, βp = n (see Chap. 1). For real gases, the interaction forces between the molecules lead to corrections to the ideal gas equation of state. We mention the classical theory by van der Waals and the systematic expansions with respect to density, called virial expansions.},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3{\_}5},
faupublication = {yes},
isbn = {978-3-030-05734-3},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {141-170},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Real} gas quantum statistics},
volume = {953},
year = {2019}
}
@article{faucris.109996964,
abstract = {We report a striking effect observed experimentally in several granular materials when shaken horizontally: The material displays a recurrent alternation between a slow inflation phase, characterized by an increase in its volume, and a fast collapse phase, when the volume abruptly returns to its original value. The frequency of such phase alternations is totally decoupled from the frequency of the external drive. We argue that the inflation and collapse alternation arises from an interplay between the mechanical stability of the material and Reynolds dilatancy due to convective motion. © 2012 American Physical Society.},
author = {Pöschel, Thorsten and Rosenkranz, Dirk E. and Gallas, Jason},
doi = {10.1103/PhysRevE.85.031307},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Recurrent} inflation and collapse in horizontally shaken granular materials},
volume = {85},
year = {2012}
}
@article{faucris.109997624,
abstract = {The oscillation of a spring may be attenuated by means of a granular damper. In difference to viscous dampers, the amplitude decays nearly linearly in time up to a finite value, from there on it decays much slower. We quantitatively explain the linear decay, which was a long-standing question. © IOP Publishing and Deutsche Physikalische Gesellschaft.},
author = {Kollmer, Jonathan and Sack, Achim and Heckel, Michael and Pöschel, Thorsten},
doi = {10.1088/1367-2630/15/9/093023},
faupublication = {yes},
journal = {New Journal of Physics},
peerreviewed = {Yes},
title = {{Relaxation} of a spring with an attached granular damper},
volume = {15},
year = {2013}
}
@article{faucris.119363464,
abstract = {Based on citation data of biologists and physicists, we reiterate that trends in statistical indicators are not reliable to unambiguously blame mathematics for the existence or lack of paper citations. We further clarify that, contrary to claims in the Comment (Higginson and Fawcett 2016 New J. Phys.18 118003), a clear statistical correlation between the number of equations and the citation success is not possible because the data is too noisy and not reliable for identifying trends unambiguously. Concerning their conclusions, we stress the well-know fact in statistics that even if correlation could be found, it by no means imply causality. Concerning their conclusions, we stress the well-know fact in statistics that even if correlation could be found, it by no means implies causality. Accordingly, to discuss ways of increasing citation rates by suppressing or hiding equations in appendices cannot be justified with statistics, even less so when based on small sets of very noisy data.},
author = {Kollmer, Jonathan and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1088/1367-2630/18/11/118004},
faupublication = {yes},
journal = {New Journal of Physics},
peerreviewed = {Yes},
title = {{Reply} to comment on ‘{Are} physicists afraid of mathematics?’},
volume = {18},
year = {2016}
}
@article{faucris.109463904,
abstract = {We investigate the residual distribution of structural defects in very tall packings of disks deposited randomly in large channels. By performing simulations involving the sedimentation of up to 50 × 10 9 particles we find all deposits to consistently show a non-zero residual density of defects obeying a characteristic power-law as a function of the channel width. This remarkable finding corrects the widespread belief that the density of defects should vanish algebraically with growing height. A non-zero residual density of defects implies a type of long-range spatial order in the packing, as opposed to only local ordering. In addition, we find deposits of particles to involve considerably less randomness than generally presumed.},
author = {Topic, Nikola and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1038/srep12703},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Residual} {Defect} {Density} in {Random} {Disks} {Deposits}},
volume = {5},
year = {2015}
}
@article{faucris.289034530,
abstract = {We develop the rheology of a dilute granular gas mixture. Motivated by the interaction of charged granular particles, we assume that the grains interact via a square shoulder and well potential. Employing a kinetic theory, we compute the temperature and the shear viscosity as a function of the shear rate. Numerical simulations confirm our results are above the critical shear rate. At a shear rate below a critical value, clustering of the particles occurs. },
author = {Yoshii, Kiwamu and Takada, Satoshi and Kurosawa, Kosuke and Pöschel, Thorsten},
doi = {10.1063/5.0132127},
faupublication = {yes},
journal = {Physics of Fluids},
month = {Jan},
note = {CRIS-Team Scopus Importer:2023-02-10},
peerreviewed = {Yes},
title = {{Rheology} of dilute granular gas mixtures where the grains interact via a square shoulder and well potential},
volume = {35},
year = {2023}
}
@article{faucris.311086696,
abstract = {During the synthesis of ring polymers, it is quite common to obtain mixtures containing both ring and linear molecules. Recent studies, including experiments and simulations, have shown that even small quantities of linear molecules can significantly influence the shape of ring polymers, ultimately altering their rheological response. To further explore this phenomenon, we investigated blends of semiflexible linear and ring filaments by using disordered assemblies of open and closed rubber bands. We employed x-ray tomography to analyze the structure of these mixtures, focusing on how the length and composition of linear bands influenced the overall mixture. In contrast to the behavior observed in fully-flexible polymers, our findings revealed that increasing the concentration of linear bands could actually decrease the average size of rings within a semiflexible ring-linear mixture. This outcome is attributable to a reduction in inter-ring threading, which naturally occurs as the proportion of rings diminishes. To validate our findings, we conducted molecular dynamics simulations on semiflexible ring-linear polymer mixtures in bulk. These simulations confirmed that our results stem from the semiflexibility of the bands or chains rather than confinement or athermal conditions.},
author = {Gómez, Leopoldo R. and García, Nicolás A. and Fernández Márquez, Juan Cruz and Pöschel, Thorsten},
doi = {10.1088/1367-2630/ace844},
faupublication = {yes},
journal = {New Journal of Physics},
keywords = {entanglements; ring-linear polymer blends; x-ray tomography},
note = {CRIS-Team Scopus Importer:2023-09-29},
peerreviewed = {Yes},
title = {{Ring}-linear mixtures of semiflexible rubber bands},
volume = {25},
year = {2023}
}
@article{faucris.107292504,
abstract = {
For most particle simulations, a time-dependent mapping between the particles’ positions and an underlying grid is an important component and is used, for example, to increase the eciency during the collision detection step. In the case of unstructured grids, which are frequently employed to handle domains of complex shape, obtaining this mapping is computationally expensive. The process can be accelerated by performing particle tracking, that is, the repeated localization of particles within a grid by means of tracking the trajectories of the particles. In fact, particle tracking is an application of event-driven particle dynamics (EDPD), hence, in this work, recent advances in stable EDPD algorithms are applied to the problem of particle tracking to address inconsistencies which arise due to numerical errors or imperfect meshes. It is illustrated how interactions of the particles with the system boundaries can be integrated into the new algorithm consistently. Additionally, it is demonstrated that the modeling of solid objects via constructive solid geometry can be combined with event-driven particle tracking algorithms to provide a fully analytical description of complex objects defining or embedded into the simulation domain. A robust particle tracking algorithm is presented, along with several optimizations with respect to the computational eciency. The capabilities of the developed method are exemplified via the simulation of a gas flow through a highly porous medium.
},
author = {Strobl, Severin and Bannerman, Marcus and Pöschel, Thorsten},
doi = {10.1016/j.cpc.2020.107229},
faupublication = {yes},
journal = {Computer Physics Communications},
pages = {107229},
peerreviewed = {Yes},
title = {{Robust} event-driven particle tracking in complex geometries},
volume = {254},
year = {2020}
}
@article{faucris.109997844,
abstract = {We show that two basic mechanical processes, the collision of particles and rolling motion of a sphere on a plane, are intimately related. According to our recent findings, the restitution coefficient for colliding spherical particles ε, which characterizes the energy loss upon collision, is directly related to the rolling friction coefficient μ for a viscous sphere on a hard plane. We quantify both coefficients in terms of material constants which allows to determine either of them provided the other is known. This relation between the coefficients may give rise to a novel experimental technique to determine alternatively the coefficient of restitution or the coefficient of rolling friction.},
author = {Brilliantov, Nikolai and Pöschel, Thorsten},
doi = {10.1007/s100510051007},
faupublication = {no},
journal = {European Physical Journal B},
keywords = {81.05.Rm Porous materials; granular materials; 83.70.Fn Granular solids},
pages = {299-301},
peerreviewed = {Yes},
title = {{Rolling} as a "continuing collision"},
volume = {12},
year = {1999}
}
@inproceedings{faucris.119712824,
abstract = {The rolling motion of a rigid cylinder on an inclined flat viscous surface is investigated and the nonlinear resistance force against rolling, F (v), is derived. For small velocities F (v) increases with velocity due to increasing deformation rate of the surface material. For larger velocity it decreases with velocity due to decreasing contact area between the rolling cylinder and the deformed surface. The cylinder is, moreover, subjected to a viscous drag force and stochastic fluctuations due to a surrounding medium (air). For this system, in a wide range of parameters we observe bistability of the rolling motion. Depending on the material parameters, increasing the noise level may lead to increasing or decreasing average velocity. © 2005 Taylor & Francis Group.},
author = {Pöschel, Thorsten and Schwager, Thomas and Brilliantov, Nikolai V. and Zaikin, A.},
booktitle = {5th International Conference on the Micromechanics of Granular Media: Powders and Grains 2005},
faupublication = {no},
isbn = {9780415383479},
pages = {1247-1251},
title = {{Rolling} friction and bistability of rolling motion},
url = {https://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=84857525008&origin=inward},
venue = {Stuttgart},
volume = {2},
year = {2005}
}
@article{faucris.118198344,
abstract = {The resistance against rolling of a rigid cylinder on a flat viscous surface is investigated. We found that the rolling-friction coefficient reveals strongly non-linear dependence on the cylinder's velocity. For low velocity the rolling-friction coefficient rises with velocity due to increasing deformation rate of the surface. For larger velocity, however, it decreases with velocity according to decreasing contact area and deformation of the surface.},
author = {Pöschel, Thorsten and Schwager, Thomas and Brilliantov, Nikolai},
doi = {10.1007/s100510050840},
faupublication = {no},
journal = {European Physical Journal B},
pages = {169-174},
peerreviewed = {Yes},
title = {{Rolling} friction of a hard cylinder on a viscous plane},
volume = {10},
year = {1999}
}
@article{faucris.109998944,
abstract = {A first-principle continuum-mechanics expression for the rolling friction coefficient is obtained for the rolling motion of a viscoelastic sphere on a hard plane. It relates the friction coefficient to the viscous and elastic constants of the sphere material. The relation obtained refers to the case when the deformation of the sphere ξ is small, the velocity of the sphere V is much less than the speed of sound in the material and when the characteristic time ξ/V is much larger than the dissipative relaxation times of the viscoelastic material. To our knowledge this is the first "first-principle" expression of the rolling friction coefficient which does not contain empirical parameters.},
author = {Brilliantov, Nikolai and Pöschel, Thorsten},
doi = {10.1209/epl/i1998-00281-7},
faupublication = {no},
journal = {EPL - Europhysics Letters},
pages = {511-516},
peerreviewed = {Yes},
title = {{Rolling} friction of a viscous sphere on a hard plane},
volume = {42},
year = {1998}
}
@article{faucris.107382044,
abstract = {Biological organisms and artificial active particles self-organize into swarms and patterns. Open questions concern the design of emergent phenomena by choosing appropriate forms of activity and particle interactions. A particularly simple and versatile system are 3D-printed robots on a vibrating table that can perform self-propelled and self-spinning motion. Here we study a mixture of minimalistic clockwise and counter-clockwise rotating robots, called rotors. Our experiments show that rotors move collectively and exhibit super-diffusive interfacial motion and phase separate via spinodal decomposition. On long time scales, confinement favors symmetric demixing patterns. By mapping rotor motion on a Langevin equation with a constant driving torque and by comparison with computer simulations, we demonstrate that our macroscopic system is a form of active soft matter.},
author = {Scholz, Christian and Engel, Michael and Pöschel, Thorsten},
doi = {10.1038/s41467-018-03154-7},
faupublication = {yes},
journal = {Nature Communications},
pages = {931},
peerreviewed = {Yes},
title = {{Rotating} robots move collectively and self-organize.},
volume = {9},
year = {2018}
}
@article{faucris.243925987,
abstract = {An integrated experimental study is presented which aims at relating the frictional properties at the particle scale to the bulk mechanical behavior for two different types of sands. We performed direct shear tests and inter-particle tests on lunar regolith simulant DNA-1A and Ottawa sand (benchmark material) under both dry and wet conditions. We found higher macroscopic friction angles for the lunar simulant in both dry and wet conditions, a smaller strength decay for Ottawa sand during reversal direct shear tests and similar strength envelopes of both materials under wet and dry conditions. Particle-scale tests evidenced higher inter-particle friction for DNA-1A in wet conditions with respect to the dry case for normal force lower than 2–3 N. For the lunar simulant, the differences between bulk and inter-particle friction appeared to be emphasized in dry condition and an evident effect of water on the friction coefficient was found only at the micro-scale.},
author = {Marzulli, Valentina and Sandeep, C. S. and Senetakis, K. and Cafaro, F. and Pöschel, Thorsten},
doi = {10.1016/j.powtec.2020.09.060},
faupublication = {yes},
journal = {Powder Technology},
keywords = {Granular material; Inter-particle friction; Lunar regolith simulant; Macroscopic friction angle; Ottawa sand; Roughness},
month = {Jan},
note = {CRIS-Team Scopus Importer:2020-10-16},
pages = {813-826},
peerreviewed = {Yes},
title = {{Scale} and water effects on the friction angles of two granular soils with different roughness},
volume = {377},
year = {2021}
}
@article{faucris.118257524,
abstract = {With the assumption of viscoelastic particle deformation, it is demonstrated that naive scaling modifies the properties of granular systems such that the original system and the scaled system might reveal quite different dynamic properties. To guarantee equivalent dynamical properties of the original and the scaled systems, material properties are modified in accordance with the scaling factor. For demonstration purposes, an example is given where the dynamics of a granular system changes significantly with system size.},
author = {Pöschel, Thorsten and Salueña, Clara and Schwager, Thomas},
doi = {10.1103/PhysRevE.64.011308},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Scaling} properties of granular materials},
volume = {64},
year = {2001}
}
@article{faucris.110013464,
abstract = {The coefficient of self-diffusion for a homogeneously cooling granular gas changes significantly if the impact-velocity dependence of the restitution coefficient ε is taken into account. For the case of a constant ε the particles spread logarithmically slowly with time, whereas a velocity-dependent coefficient yields a power law time dependence. The impact of the difference in these time dependences on the properties of a freely cooling granular gas is discussed.},
author = {Brilliantov, Nikolai and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.61.1716},
faupublication = {no},
journal = {Physical Review E},
pages = {1716-1721},
peerreviewed = {Yes},
title = {{Self}-diffusion in granular gases},
volume = {61},
year = {2000}
}
@article{faucris.124183884,
abstract = {We study the diffusion of tracers (self-diffusion) in a homogeneously cooling gas of dissipative particles, using the Green-Kubo relation and the Chapman-Enskog approach. The dissipative particle collisions are described by the coefficient of restitution ε which for realistic material properties depends on the impact velocity. First, we consider self-diffusion using a constant coefficient of restitution, ε=const, as frequently used to simplify the analysis. Second, self-diffusion is studied for a simplified (stepwise) dependence of ε on the impact velocity. Finally, diffusion is considered for gases of realistic viscoelastic particles. We find that for ε=const both methods lead to the same result for the self-diffusion coefficient. For the case of impact-velocity dependent coefficients of restitution, the Green-Kubo method is, however, either restrictive or too complicated for practical application, therefore we compute the diffusion coefficient using the Chapman-Enskog method. We conclude that in application to granular gases, the Chapman-Enskog approach is preferable for deriving kinetic coefficients. © 2005 American Institute of Physics.},
author = {Brilliantov, Nikolai V. and Pöschel, Thorsten},
doi = {10.1063/1.1889266},
faupublication = {no},
journal = {Chaos},
peerreviewed = {Yes},
title = {{Self}-diffusion in granular gases: {Green}-{Kubo} versus {Chapman}-{Enskog}},
volume = {15},
year = {2005}
}
@article{faucris.109876404,
abstract = {Antiperiodic oscillations forming infinite cascades of spirals were recently found experimentally and numerically in the control parameter space of an autonomous electronic circuit. They were discovered while recording one specific voltage of the circuit. Here, we show that such regular self-organization may be measured in any of the four variables of the circuit. Although the relative size of individual phases, their boundaries and the number of peaks of each characteristic oscillation depends on the physical quantity used to record them, the global structural organization of the complex phase diagrams is an invariant of the circuit. Tunable families of antiperiodic oscillations cast fresh light on new intricate behavior of nonlinear systems and open the possibility of studying hitherto unobserved phenomena.},
author = {Freire, J. G. and Cabeza, C. and Marti, A. C. and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1140/epjst/e2014-02299-2},
faupublication = {yes},
journal = {European Physical Journal - Special Topics},
pages = {2857-2867},
peerreviewed = {Yes},
title = {{Self}-organization of antiperiodic oscillations},
volume = {223},
year = {2014}
}
@article{faucris.109809304,
abstract = {A granular gas in gravity heated from below develops a certain stationary density profile. When the heating is switched off, the granular gas collapses. We investigate the process of sedimentation using computational hydrodynamics, based on the Jenkins-Richman theory, and find that the process is significantly more complex than generally acknowledged. In particular, during its evolution, the system passes several stages which reveal distinct spatial regions of inertial (supersonic) and diffusive (subsonic) dynamics. During the supersonic stages, characterized by Mach>1, the system develops supersonic shocks which are followed by a steep front of the hydrodynamic fields of temperature and density, traveling upward.},
author = {Almazan Torres, Lidia and Serero, Dan and Salueña, Clara and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.91.062214},
faupublication = {yes},
journal = {Physical Review E - Statistical, Nonlinear, and Soft Matter Physics},
keywords = {granular gas},
peerreviewed = {Yes},
title = {{Self}-organized shocks in the sedimentation of a granular gas},
volume = {91},
year = {2015}
}
@article{faucris.320055852,
abstract = {Granular materials show inhomogeneous flows characterized by strain localization. When strain is localized in a sheared granular material, rigid regions of a nearly undeformed state are separated by shear bands, where the material yields and flows. The characteristics of the shear bands are determined by the geometry of the system, the micromechanical material properties, and the kinematics at the particle level. For a split-bottom shear cell, recent experimental work has shown that mixtures of hard, frictional and soft, nearly frictionless particles exhibit wider shear zones than samples with only one of the two components. To explain this finding, we investigate the shear zone properties and the stress response of granular mixtures using discrete element simulations. We show that both interparticle friction and elastic modulus determine the shear-band properties and packing density of granular mixtures of various mixing ratios, but their stress response depends strongly on the interparticle friction. Our study provides a fundamental understanding of the micromechanics of shear band formation in granular mixtures.},
author = {Singh, Aditya Pratap and Angelidakis, Vasileios and Pöschel, Thorsten and Roy, Sudeshna},
doi = {10.1039/d4sm00100a},
faupublication = {yes},
journal = {Soft Matter},
note = {CRIS-Team Scopus Importer:2024-03-22},
peerreviewed = {Yes},
title = {{Shear} zones in granular mixtures of hard and soft particles with high and low friction},
year = {2024}
}
@article{faucris.110020284,
abstract = {We investigate the flow of granular material in a rotating cylinder numerically using molecular dynamics in two dimensions. The particles are described by a new model which allows to simulate geometrically complicated shaped grains. The results of the simulation agree significantly better with experiments than the results which are based on circular particles. © 1995.},
author = {Buchholtz, Volkhard and Pöschel, Thorsten and Tillemans, Hans-Jürgen},
doi = {10.1016/0378-4371(95)00045-9},
faupublication = {no},
journal = {Physica A-Statistical Mechanics and Its Applications},
pages = {199-212},
peerreviewed = {Yes},
title = {{Simulation} of rotating drum experiments using non-circular particles},
volume = {216},
year = {1995}
}
@article{faucris.267808770,
abstract = {Granular jamming has been identified as a fundamental mechanism for the operation of robotic grippers. In this work, we show, that soft particles like expanded polystyrene beads lead to significantly larger gripping forces in comparison to rigid particles. In contradiction to naive expectation, the combination of jamming and elasticity gives rise to very different properties of the jammed phase, compared to hard-particle systems. This may be of interest also beyond the application in robotic grippers.},
author = {Götz, Holger and Santarossa, Angel and Sack, Achim and Pöschel, Thorsten and Müller, Patric},
doi = {10.1007/s10035-021-01193-4},
faupublication = {yes},
journal = {Granular Matter},
keywords = {Granular gripper; Granular jamming; Soft robotics},
note = {CRIS-Team Scopus Importer:2022-01-07},
peerreviewed = {Yes},
title = {{Soft} particles reinforce robotic grippers: robotic grippers based on granular jamming of soft particles},
volume = {24},
year = {2022}
}
@article{faucris.317018328,
abstract = {We introduce SPIRAL, a third-order integration algorithm for the rotational motion of extended bodies. It requires only one force calculation per time step, does not require quaternion normalization at each time step, and can be formulated for both leapfrog and synchronous integration schemes, making it compatible with many particle simulation codes. The stability and precision of SPIRAL exceed those of state-of-the-art algorithms currently used in popular DEM codes such as YADE, MERCURYDPM, LIGGGHTS, PFC, and more, at only slightly higher computational cost. Also, beyond DEM, we see potential applications in all numerical simulations that involve the 3D rotation of extended bodies.},
author = {del Valle, Carlos Andrés and Angelidakis, Vasileios and Roy, Sudeshna and Muñoz, José Daniel and Pöschel, Thorsten},
doi = {10.1016/j.cpc.2023.109077},
faupublication = {yes},
journal = {Computer Physics Communications},
keywords = {Numerical integration of the equation of rotational motion; Particle simulation; Discrete element method (DEM); Molecular dynamics (MD)},
note = {CRIS-Team Scopus Importer:2024-01-26},
peerreviewed = {Yes},
title = {{SPIRAL}: {An} efficient algorithm for the integration of the equation of rotational motion},
url = {https://www.sciencedirect.com/science/article/pii/S0010465523004228},
volume = {297},
year = {2024}
}
@article{faucris.262971006,
abstract = {We study here the spontaneous clustering of a submonolayer of grains under horizontal circular shaking. The clustering of grains occurs when increasing the oscillation amplitude beyond a threshold. The dense area travels in a circular fashion at the driving frequency, which even exceeds the speed of driving. It turns out that the observed clustering is due to the formation of density waves. The analysis of a phenomenological model shows that the instability of the uniform density profile arises by increasing the oscillation amplitude and captures the non-monotonic dependence of the transition amplitude of the clustering on the global density of the system. Here, the key ingredient is that the velocity of individual grains increases with the local density. The interplay of the dissipative particle-particle interaction and frictional driving of the substrate results in this dependence, which is tested with discrete element method simulations.},
author = {Zhao, Song Chuan and Pöschel, Thorsten},
doi = {10.1063/5.0056143},
faupublication = {yes},
journal = {Physics of Fluids},
note = {CRIS-Team Scopus Importer:2021-08-20},
peerreviewed = {Yes},
title = {{Spontaneous} formation of density waves in granular matter under swirling excitation},
volume = {33},
year = {2021}
}
@article{faucris.255355592,
abstract = {OBJECTIVES: Microcomputed tomography (µCT) is a powerful analytical tool for non-invasive structural analysis. The stability of drug substances and formulations subjected to X-ray radiation may be a concern in the industry. This study examines the effect of X-ray radiation on the stability of freeze-dried pharmaceuticals. The investigation is a proof of concept study for the safety of µCT X-ray radiation doses during the non-destructive investigation of freeze-dried products. METHODS: Different formulations of clotrimazole, insulin and l-lactate dehydrogenase were freeze-dried and the products exposed to a defined dose of radiation by µCT. Conservative freeze-drying conditions were used. Irradiated and normal samples were analysed for their stability directly after freeze-drying and after stability testing. KEY FINDINGS: The stability of model compounds was well maintained during freeze-drying. Some degradation of all compounds occurred during accelerated stability testing. The results showed no differences between the irradiated and normal state directly after freeze-drying and accelerated stability testing. CONCLUSIONS: No evidence of a detrimental effect of 100 Gy X-ray exposure on a model small molecule, peptide and protein compound was found while useful structural information could be obtained. Consequently, the technology may be useful as a non-destructive tool for product inspections if the formulation proves stable.},
author = {Wenzel, Tim and Sack, Achim and Müller, Patrick and Pöschel, Thorsten and Schuldt-Lieb, Sonja and Gieseler, Henning},
doi = {10.1093/jpp/rgaa004},
faupublication = {yes},
journal = {Journal of Pharmacy and Pharmacology},
keywords = {freeze-drying; inspection; micro computed tomography; morphology; stability},
note = {CRIS-Team Scopus Importer:2021-04-16},
pages = {212-220},
peerreviewed = {Yes},
title = {{Stability} of freeze-dried products subjected to microcomputed tomography radiation doses},
volume = {73},
year = {2021}
}
@article{faucris.114386844,
abstract = {Event-driven particle dynamics is a fast and precise method to simulate particulate systems of all scales. In this work it is demonstrated that, despite the high accuracy of the method, the finite machine precision leads to simulations entering invalid states where the dynamics are undefined. A general event-detection algorithm is proposed which handles these situations in a stable and efficient manner. This requires a definition of the dynamics of invalid states and leads to improved algorithms for event-detection in hard-sphere systems.},
author = {Bannerman, Marcus and Strobl, Severin and Formella, Arno and Pöschel, Thorsten},
doi = {10.1007/s40571-014-0021-8},
faupublication = {yes},
journal = {Computational Particle Mechanics},
pages = {191--198},
peerreviewed = {Yes},
title = {{Stable} algorithm for event detection in event-driven particle dynamics},
volume = {1},
year = {2014}
}
@article{faucris.122074304,
abstract = {Following the recent development of a stable event-detection algorithm for hard-sphere systems, the implications of more complex interaction models are examined. The relative location of particles leads to ambiguity when it is used to determine the interaction state of a particle in stepped potentials, such as the square-well model. To correctly predict the next event in these systems, the concept of an additional state that is tracked separately from the particle position is introduced and integrated into the stable algorithm for event detection.},
author = {Strobl, Severin and Bannerman, Marcus and Pöschel, Thorsten},
doi = {10.1007/s40571-016-0106-7},
faupublication = {yes},
journal = {Computational Particle Mechanics},
keywords = {DEM; Event-driven; Molecular dynamics; Square well; Stepped potential; Collision detection;},
pages = {383–388},
peerreviewed = {Yes},
title = {{Stable} algorithm for event detection in event-driven particle dynamics: logical states},
volume = {3},
year = {2016}
}
@article{faucris.110024464,
abstract = {The static as well as the dynamic behavior of granular material are determined by dynamic and static friction. There are well known methods to inlcude static friction in molecular dynamics simulations using scarcely understood forces. We propose an ansatz based on the geometrical shape of nonspherical particles which does not involve an explicit expression for static friction. It is shown that the simulations based on this model are close to experimental results. © 1993 The American Physical Society.},
author = {Pöschel, Thorsten and Buchholtz, Volkhard},
doi = {10.1103/PhysRevLett.71.3963},
faupublication = {no},
journal = {Physical Review Letters},
pages = {3963-3966},
peerreviewed = {Yes},
title = {{Static} friction phenomena in granular materials: {Coulomb} law versus particle geometry},
volume = {71},
year = {1993}
}
@article{faucris.113990404,
abstract = {We present an efficient event-driven algorithm for sequential ballistic deposition of complex-shaped rigid particles. Each of the particles is constructed from hard spheres (typically 5.1000) of variable radii. The sizes and relative positions of the spheres may mutually overlap and can be chosen such that the surface of the resulting particle appears relatively smooth. In the sequential deposition process, by performing steps of rolling and linear motion, the particles move along the steepest descent in a landscape formed by the boundaries and previously deposited particles. The computer time for the simulation of a deposition process depends on the total number of spheres but only weakly on the sizes and shapes of the particles. The proposed algorithm generalizes the Visscher-Bolsterli algorithm [1] which is frequently used for packing of spheres, to non-spherical particles. The proposed event-driven algorithm allows simulations of multi-million particle systems using desktop computers.},
author = {Topic, Nikola and Pöschel, Thorsten},
doi = {10.1016/j.jcp.2015.12.052},
faupublication = {yes},
journal = {Journal of Computational Physics},
keywords = {Complex shaped particles; Event-driven algorithm; Non-spherical particles; Steepest descent ballistic deposition},
pages = {421-437},
peerreviewed = {Yes},
title = {{Steepest} descent ballistic deposition of complex shaped particles},
volume = {308},
year = {2016}
}
@article{faucris.119200444,
abstract = {We study the global organization of oscillations in sigmoidal maps, a class of models which reproduces complex locking behaviors commonly observed in lasers, neurons, and other systems which display spiking, bursting, and chaotic sequences of spiking and bursting. We find periodic oscillations to emerge organized regularly according to the elusive Stern-Brocot tree, a symmetric and more general tree which contains the better-known asymmetric Farey tree as a sub-tree. The Stern-Brocot tree provides a natural and encompassing organization to classify nonlinear oscillations. The mathematical algorithm for generating both trees is exactly the same, differing only in the initial conditions. Such degeneracy suggests that the wrong tree might have been attributed to locking phenomena reported in some of the earlier works. © Copyright EPLA, 2012.},
author = {Freire, J. G. and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1209/0295-5075/100/48002},
faupublication = {yes},
journal = {EPL - Europhysics Letters},
peerreviewed = {Yes},
title = {{Stern}-{Brocot} trees in spiking and bursting of sigmoidal maps},
volume = {100},
year = {2012}
}
@article{faucris.109879044,
abstract = {We consider the collision of a rough sphere with a plane by detailed analysis of the collision geometry. Using stochastic methods, the effective coefficient of restitution may be described as a fluctuating quantity whose probability density follows an asymmetric Laplace distribution. This result agrees with recent experiments by Montaine [Phys. Rev. E 84, 041306 (2011)]PLEEE81539-375510.1103/PhysRevE.84.041306. © 2014 American Physical Society.},
author = {Gunkelmann, Nina and Montaine, Marina and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.89.022205},
faupublication = {yes},
journal = {Physical Review E - Statistical, Nonlinear, and Soft Matter Physics},
peerreviewed = {Yes},
title = {{Stochastic} behavior of the coefficient of normal restitution},
volume = {89},
year = {2014}
}
@incollection{faucris.223574545,
abstract = {The dynamics of rapid granular flows is governed by dissipative interactions of particles with each other and with the system walls. To adequately describe these interactions, roughness and particle shape must be taken into account. The coefficient of restitution for arbitrary particles thus depends not only on material properties and impact velocity but also on the angular orientation at the instant of the collision. By measurements of the coefficient of restitution from the sound signal emitted by a sphere bouncing repeatedly off the ground, it was found that small deviations from the perfect shape of the sphere lead to large measurement errors. Using stochastic methods, the effective coefficient of restitution for the collision of a rough sphere with a plane was described as a fluctuating quantity, characterized by a rather uncommon probability density function. It was shown that modelling the coefficient of restitution as a stochastic variable significantly affects the dynamics of particles under rapid granular flows. The decay of temperature of rapid granular flows in the homogeneous cooling state deviates from Haff's law for gases of particles interacting via a constant coefficient of restitution also from the scaling law for gases of viscoelastic particles.
We report startling evidence of a systematic onset of periodic structures in large piles of disks deposited between rigid walls, independently of the pile width, observed in numerically constructed monodisperse packings with up to 107 disks. Disordered transient phases preceding the periodicity onset are found to obey power-laws as a function of the channel height. Independently of the width, we invariably find packings to be asymptotically periodic after disordered transients which, however, may become very large as the channel width grows without bound. The probability density of finding periodic structures of a given period displays a series of discrete peaks which, however, are washed out when the channel width grows indefinitely.
},
author = {Topic, Nikola and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1103/PhysRevLett.120.148002},
faupublication = {yes},
journal = {Physical Review Letters},
pages = {148002},
peerreviewed = {Yes},
title = {{Systematic} {Onset} of {Periodic} {Patterns} in {Random} {Disk} {Packings}},
volume = {120},
year = {2018}
}
@article{faucris.110032604,
abstract = {The decay of temperature of a force-free granular gas in the homogeneous cooling state depends on the specific model for particle interaction. For the case of rough spheres, in recent experimental and theoretical work, the coefficient of restitution was characterized as a fluctuating quantity. We show that for such particles, the decay of temperature with time follows the law which deviates from Haff's law, T ∼ t, obtained for gases of particles interacting via a constant coefficient of restitution also from obtained for gases of viscoelastic particles. Our results are obtained from kinetic theory and are in very good agreement with Monte Carlo simulations. © IOP Publishing and Deutsche Physikalische Gesellschaft.},
author = {Gunkelmann, Nina and Serero, Dan and Pöschel, Thorsten},
doi = {10.1088/1367-2630/15/9/093030},
faupublication = {yes},
journal = {New Journal of Physics},
peerreviewed = {Yes},
title = {{Temperature} of a granular gas with regard to the stochastic nature of particle interactions},
volume = {15},
year = {2013}
}
@article{faucris.110034144,
abstract = {Collisions between granular particles are irreversible processes which cause dissipation of mechanical energy by fragmentation or heating of the colliders. The knowledge of these phenomena is essential for the understanding of the behaviour of complex systems of granular particles. We have developed a model for inelastic collisions of granular particles and calculated the velocity restitution coefficients, which describe all possible collisions in the system. The knowledge of these coefficients allows for event-driven many-particle simulations which cannot be performed in the frame of molecular dynamics. This approach has the advantage that very large particle numbers can be treated which are necessary for the understanding of intrinsic large-scale phenomena in granular systems.},
author = {Brilliantov, Nikolai and Spahn, Frank and Hertzsch, Jan-Martin and Pöschel, Thorsten},
doi = {10.1016/0378-4371(96)00099-4},
faupublication = {no},
journal = {Physica A-Statistical Mechanics and Its Applications},
pages = {417-424},
peerreviewed = {Yes},
title = {{The} collision of particles in granular systems},
volume = {231},
year = {1996}
}
@article{faucris.110035904,
abstract = {The kinetic energy distribution function satisfying the Boltzmann equation is studied analytically and numerically for a system of inelastic hard spheres in the case of binary collisions. Analytically, this function is shown to have a similarity form in the simple cases of uniform or steady-state flows. This determines the region of validity of hydrodynamic description. The latter is used to construct the phase diagram of granular systems and discriminate between clustering instability and inelastic collapse. The molecular dynamics results support analytical results, but also exhibit a novel fluctuational breakdown of mean-field descriptions.},
author = {Pöschel, Thorsten and Esipov, Sergei E.},
doi = {10.1007/BF02183630},
faupublication = {no},
journal = {Journal of Statistical Physics},
keywords = {Boltzmann equation; Granular hydrodynamics; Granular temperature},
pages = {1385-1395},
peerreviewed = {Yes},
title = {{The} granular phase diagram},
volume = {86},
year = {1997}
}
@article{faucris.122915804,
abstract = {A representation of the genetic code as a six-dimensional Boolean hypercube is described. This structure is the result of the hierarchical order of the interaction energies of the bases in codon-anticodon recognition. In this paper it is applied to study molecular evolution in vivo and in vitro. In the first case we compared aligned positions in homologous protein sequences and found two different behaviors: (a) There are sites in which the different amino acids may be explained by one or two 'attractor nodes' (coding for the dominating amino acid(s)) and their one-bit neighbors in the codon hypercube; and (b) There are sites in which the amino acids correspond to codons located in closed paths in the hypercube. In the second case we studied the 'Sexual PCR' experiment described by Stemmer and found that the success of this combination of usual PCR and recombination is in part due to the Gray code structure of the genetic code.},
author = {Jiménez-Montaño, Miguel A. and de la Mora-Basáñez, Carlos R. and Pöschel, Thorsten},
doi = {10.1016/0303-2647(96)01605-X},
faupublication = {no},
journal = {Biosystems},
keywords = {Genetic code; In vitro and in vivo; Molecular evolution; Six dimensional Boolean hypercube},
pages = {117-125},
peerreviewed = {Yes},
title = {{The} hypercube structure of the genetic code explains conservative and non-conservative aminoacid substitutions in vivo and in vitro},
volume = {39},
year = {1996}
}
@article{faucris.114680544,
abstract = {Granular heaps of particles created by deposition of mono-disperse particles raining from an extended
source of finite size are characterized by a non-homogeneous field of density. It was speculated that this
inhomogeneity is due to the transient shape of the sediment during the process of construction of the
heap, thus reflecting the history of the creation of the heap. By comparison of structural characteristics of
the heap with sediments created on top of inclined planes exploiting the method of Minkowski tensors,
we provide further evidence to support this hypothesis. Moreover, for the case of sediments generated by
homogeneous rain on surfaces, we provide relationships between the inclination of the surface and the
Minkowski measures characterizing the isotropy of local particle environments.},
author = {Topic, Nikola and Schaller, Fabian and Schröder-Turk, Gerd and Pöschel, Thorsten},
doi = {10.1039/c5sm03114a},
faupublication = {yes},
journal = {Soft Matter},
peerreviewed = {Yes},
title = {{The} microscopic structure of mono-disperse granular heaps and sediments of particles on inclined surfaces},
year = {2016}
}
@article{faucris.107356744,
abstract = {We engineered an automated biomechatronics system, MyoRobot, for robust objective and versatile assessment of muscle or polymer materials (bio-)mechanics. It covers multiple levels of muscle biosensor assessment, e.g. membrane voltage or contractile apparatus Ca2+ ion responses (force resolution 1 µN, 0–10 mN for the given sensor; [Ca2+] range ~ 100 nM–25 µM). It replaces previously tedious manual protocols to obtain exhaustive information on active/passive biomechanical properties across various morphological tissue levels. Deciphering mechanisms of muscle weakness requires sophisticated force protocols, dissecting contributions from altered Ca2+ homeostasis, electro-chemical, chemico-mechanical biosensors or visco-elastic components. From whole organ to single fibre levels, experimental demands and hardware requirements increase, limiting biomechanics research potential, as reflected by only few commercial biomechatronics systems that can address resolution, experimental versatility and mostly, automation of force recordings. Our MyoRobot combines optical force transducer technology with high precision 3D actuation (e.g. voice coil, 1 µm encoder resolution; stepper motors, 4 µm feed motion), and customized control software, enabling modular experimentation packages and automated data pre-analysis. In small bundles and single muscle fibres, we demonstrate automated recordings of (i) caffeine-induced-, (ii) electrical field stimulation (EFS)-induced force, (iii) pCa-force, (iv) slack-tests and (v) passive length-tension curves. The system easily reproduces results from manual systems (two times larger stiffness in slow over fast muscle) and provides novel insights into unloaded shortening velocities (declining with increasing slack lengths). The MyoRobot enables automated complex biomechanics assessment in muscle research. Applications also extend to material sciences, exemplarily shown here for spider silk and collagen biopolymer},
author = {Haug, Michael and Reischl, Barbara and Prölß, Gerhard and Pollmann, Charlotte and Buckert, Thomas and Keidel, Christian and Schürmann, Sebastian and Hock, Magdalena and Rupitsch, Stefan and Heckel, Michael and Pöschel, Thorsten and Scheibel, T and Haynl, C and Kiriaev, L and Head, Stewart I. and Friedrich, Oliver},
doi = {10.1016/j.bios.2017.12.003},
faupublication = {yes},
journal = {Biosensors and Bioelectronics},
pages = {589-599},
peerreviewed = {Yes},
title = {{The} {MyoRobot}: {A} novel automated biomechatronics system to assess voltage/{Ca2}+ biosensors and active/passive biomechanics in muscle and biomaterials},
volume = {102},
year = {2018}
}
@article{faucris.223555902,
abstract = {Mutations in the Des gene coding for the muscle-specific intermediate filament protein desmin lead to myopathies and cardiomyopathies. We previously generated a R349P desmin knock-in mouse strain as a patient-mimicking model for the corresponding most frequent human desmin mutation R350P. Since nothing is known about the age-dependent changes in the biomechanics of affected muscles, we investigated the passive and active biomechanics of small fiber bundles from young (17–23 wks), adult (25–45 wks) and aged (>60 wks) heterozygous and homozygous R349P desmin knock-in mice in comparison to wild-type littermates. We used a novel automated biomechatronics platform, the MyoRobot, to perform coherent quantitative recordings of passive (resting length-tension curves, visco-elasticity) and active (caffeine-induced force transients, pCa-force, ‘slack-tests’) parameters to determine age-dependent effects of the R349P desmin mutation in slow-twitch soleus and fast-twitch extensor digitorum longus small fiber bundles. We demonstrate that active force properties are not affected by this mutation while passive steady-state elasticity is vastly altered in R349P desmin fiber bundles compatible with a pre-aged phenotype exhibiting stiffer muscle preparations. Visco-elasticity on the other hand, was not altered. Our study represents the first systematic age-related characterization of small muscle fiber bundle preparation biomechanics in conjunction with inherited desminopathy.},
author = {Haug, Michael and Meyer, Charlotte and Reischl, Barbara and Prölß, Gerhard and Vetter, Karoline and Iberl, Julian and Nübler, Stefanie and Schürmann, Sebastian and Rupitsch, Stefan and Heckel, Michael and Pöschel, Thorsten and Winter, Lilli and Herrmann, Harald and Clemen, Christoph S. and Schröder, Rolf and Friedrich, Oliver},
doi = {10.1038/s41598-019-46723-6},
faupublication = {yes},
journal = {Scientific Reports},
note = {CRIS-Team Scopus Importer:2019-08-02},
peerreviewed = {Yes},
title = {{The} {MyoRobot} technology discloses a premature biomechanical decay of skeletal muscle fiber bundles derived from {R349P} desminopathy mice},
volume = {9},
year = {2019}
}
@article{faucris.110038324,
abstract = {The most striking phenomenon in the dynamics of granular gases is the formation of clusters and other structures. We investigate a gas of dissipatively colliding particles with a velocity dependent coefficient of restitution where cluster formation occurs as a transient phenomenon. Although for small impact velocity the particles collide elastically, surprisingly the temperature converges to zero. © 2005 IOP Publishing Ltd.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai V. and Schwager, Thomas},
doi = {10.1088/0953-8984/17/24/021},
faupublication = {no},
journal = {Journal of Physics: Condensed Matter},
peerreviewed = {Yes},
title = {{Transient} clusters in granular gases},
volume = {17},
year = {2005}
}
@article{faucris.110045584,
abstract = {A force-free granular gas was considered with an impact-velocity-dependent coefficient of restitution as it followed from the model of viscoelastic particles. Structural formation in this system was studied by means of three independent methods: event-driven molecular dynamics (MD), numerical solution of the hydrodynamic (HD) equations, and linear stability analysis of the HD equations. It was observed that cluster growth resulted in the decrease in gas density with time. It was found that structural formulation occurred in force-free granular gases only as a transient process.},
author = {Brilliantov, Nikolai V. and Salueña, Clara and Schwager, Thomas and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.93.134301},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Transient} structures in a granular gas},
volume = {93},
year = {2004}
}
@article{faucris.119744284,
abstract = {In a granular gas of rough particles the axis of rotation is shown to be correlated with the translational velocity of the particles. The average relative orientation of angular and linear velocities depends on the parameters which characterize the dissipative nature of the collision. We derive a simple theory for these correlations and validate it with numerical simulations for a wide range of coefficients of normal and tangential restitution. The limit of smooth spheres is shown to be singular: even an arbitrarily small roughness of the particles gives rise to orientational correlations. © 2007 The American Physical Society.},
author = {Brilliantov, Nikolai V. and Pöschel, Thorsten and Kranz, W. T. and Zippelius, A.},
doi = {10.1103/PhysRevLett.98.128001},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Translations} and rotations are correlated in granular gases},
volume = {98},
year = {2007}
}
@article{faucris.269462666,
abstract = {We consider a dilute gas of electrically charged granular particles in the homogeneous cooling state. We derive the energy dissipation rate and the transport coefficients from the inelastic Boltzmann equation. We find that the deviation of the velocity distribution function from the Maxwellian yields overshoots of the transport coefficients, and especially, the negative peak of the Dufour-like coefficient, mu, in the intermediate granular temperature regime. We perform the linear stability analysis and investigate the granular temperature dependence of each mode, where the instability mode is found to change against the granular temperature. The molecular dynamics simulations are also performed to compare the result with that from the kinetic theory.},
author = {Takada, Satoshi and Serero, Dan and Pöschel, Thorsten},
doi = {10.1017/jfm.2022.37},
faupublication = {yes},
journal = {Journal of Fluid Mechanics},
note = {CRIS-Team WoS Importer:2022-02-11},
peerreviewed = {Yes},
title = {{Transport} coefficients for granular gases of electrically charged particles},
volume = {935},
year = {2022}
}
@article{faucris.110047124,
abstract = {The main precondition of simulating systems of hard particles by means of event-driven modeling is the assumption of instantaneous collisions. The aim of this paper is to quantify the deviation of event-driven modeling from the solution of Newton's equation of motion using a paradigmatic example: If a tennis ball is held above a basketball with their centers vertically aligned, and the balls are released to collide with the floor, the tennis ball may rebound at a surprisingly high speed. We show in this article that the simple textbook explanation of this effect is an oversimplification, even for the limit of perfectly elastic particles. Instead, there may occur a rather complex scenario including multiple collisions which may lead to a very different final velocity as compared with the velocity resulting from the oversimplified model. © 2011 American Physical Society.},
author = {Müller, Patric and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.83.041304},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Two}-ball problem revisited: {Limitations} of event-driven modeling},
volume = {83},
year = {2011}
}
@article{faucris.121151624,
abstract = {We investigate the average turbulent wind field over a barchan dune by means of Computational Fluid Dynamics. We find that the fractional speed-up ratio of the wind velocity over the three-dimensional barchan shape differs from the one obtained from two-dimensional calculations of the airflow over the longitudinal cut along the dune's symmetry axis - that is, over the equivalent transverse dune of same size. This finding suggests that the modeling of the airflow over the central slice of barchan dunes is insufficient for the purpose of the quantitative description of barchan dune dynamics as three-dimensional flow effects cannot be neglected.},
author = {Michelsen, Britt and Strobl, Severin and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1038/srep16572},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Two}-dimensional airflow modeling underpredicts the wind velocity over dunes},
volume = {5},
year = {2015}
}
@article{faucris.118403604,
abstract = {The velocity distribution in a homogeneously cooling granular gas has been studied in the viscoelastic regime, when the restitution coefficient of colliding particles depends on the impact velocity. We show that for viscoelastic particles a simple scaling hypothesis is violated, i.e., that the time dependence of the velocity distribution does not scale with the mean square velocity as in the case of particles interacting via a constant restitution coefficient. The deviation from the Maxwellian distribution does not depend on time monotonically. For the case of small dissipation we detected two regimes of evolution of the velocity distribution function: Starting from the initial Maxwellian distribution, the deviation first increases with time on a collision time scale saturating at some maximal value; then it decays to zero on a much larger time scale which corresponds to the temperature relaxation. For larger values of the dissipation parameter there appears an additional intermediate relaxation regime. Analytical calculations for small dissipation agree well with the results of a numerical analysis.},
author = {Brilliantov, Nikolai and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.61.5573},
faupublication = {no},
journal = {Physical Review E},
pages = {5573-5587},
peerreviewed = {Yes},
title = {{Velocity} distribution in granular gases of viscoelastic particles},
volume = {61},
year = {2000}
}
@article{faucris.119404164,
abstract = {
The theory of homogeneously driven granular gases of hard particles predicts that the stationary state is characterized by a velocity distribution function with overpopulated high-energy tails as compared to the exponential decay valid for molecular gases. While this fundamental theoretical result was confirmed by numerous numerical simulations, an experimental confirmation is still missing. Using self-rotating active granular particles, we find a power-law decay of the velocity distribution whose exponent agrees well with the theoretic prediction.
},
author = {Scholz, Christian and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.118.198003},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {unknown},
title = {{Velocity} distribution of a homogeneously driven two-dimensional granular gas},
volume = {118},
year = {2017}
}
@article{faucris.110053724,
abstract = {The onset of surface fluidization of granular material in a vertically vibrated container, z = A cos (ωt), is studied experimentally. Recently, for a column of spheres it has been theoretically found (see T. Pöschel, T. Schwager, C. Salueña, Phys. Rev. E 62, 1361 (2000)) that the particles lose contact if a certain condition for the acceleration amplitude z̈ ≡ Aω/g = f(ω) holds. This result is in disagreement with other findings where the criterion z̈ = z̈ = const was found to be the criterion of fluidization. We show that for a column of spheres a critical acceleration is not a proper criterion for fluidization and compare the results with theory.},
author = {Renard, S. and Schwager, Thomas and Pöschel, Thorsten and Salueña, Clara},
doi = {10.1007/s101890170133},
faupublication = {no},
journal = {European Physical Journal E},
pages = {233-239},
peerreviewed = {Yes},
title = {{Vertically} shaken column of spheres. {Onset} of fluidization},
volume = {4},
year = {2001}
}
@article{faucris.107702584,
abstract = {When a narrow tube inserted into a static container filled with particles is subjected to vertical vibration, the particles rise in the tube, much resembling the ascending motion of a liquid column in a capillary tube. To gain insights on the particle dynamics dictating this phenomenon – which we term granular capillarity – we numerically investigate the system using the Discrete Element Method (DEM). We reproduce the dynamical process of the granular capillarity and analyze the vertical motion of the individual particles in the tube, as well as the average vertical velocities of the particles. Our simulations show that the height of the granular column fluctuates in a periodic or period-doubling manner as the tube vibrates, until a steady-state (capillary) height is reached. Moreover, our results for the average vertical velocity of the particles in the tube at different radial positions suggest that granular convection is one major factor underlying the particle-based dynamics that lead to the granular capillarity phenomenon.},
author = {Fan, Fengxian and Liu, Ju and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1051/epjconf/201714016008},
faupublication = {yes},
journal = {EPJ Web of Conferences},
peerreviewed = {unknown},
title = {{Vertical} motion of particles in vibration-induced granular capillarity},
volume = {140},
year = {2017}
}
@article{faucris.110054824,
abstract = {Numerical simulations of a dissipative hard sphere gas reveal a dependence of the cooling rate on correlation of the particle velocities due to inelastic collisions. We propose a coefficient which characterizes the velocity correlations in the two-particle velocity distribution function and express the temperature decay rate in terms of this coefficient. The analytical results are compared with numerics.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai and Schwager, Thomas},
doi = {10.1142/S012918310200411X},
faupublication = {no},
journal = {International Journal of Modern Physics C},
keywords = {Dissipative gases; Granular gases; Kinetic gas theory; Many-particle systems; Velocity correlations},
pages = {1263-1272},
peerreviewed = {Yes},
title = {{Violation} of molecular chaos in dissipative gases},
volume = {13},
year = {2002}
}
@article{faucris.119943164,
abstract = {
A flowing hourglass changes its weight in the course of time because of the accelerated motion of its center of mass. While this insight is not new, it is frequently said that the effect is tiny and hardly measurable. Here we present a simple experiment which allows to monitor the weight as a function of time revealing different stages, in quantitative agreement with theory.
},
author = {Sack, Achim and Pöschel, Thorsten},
doi = {10.1119/1.4973527},
faupublication = {yes},
journal = {American Journal of Physics},
month = {Jan},
peerreviewed = {Yes},
title = {{Weight} of an {Hourglass} – {Theory} and {Experiment} in {Quantitative} {Comparison}},
volume = {85},
year = {2017}
}
@article{faucris.228155735,
abstract = {We present an X-ray device for use under conditions of weightlessness to produce high-speed radiograms and tomograms. The device is equipped with two detectors of different resolutions, a high temporal resolution-small area detector (4 Mpix within 13 × 13 mm2) and a low temporal resolution-large area detector (3 Mpix within 145 × 115 mm2). Using the high temporal resolution detector, the device achieves a recording rate of up to 25 655 radiograms per second, while using a low temporal resolution detector, up to 86 radiograms can be recorded per second. For the first time, we could record complete X-ray tomograms in microgravity aboard a parabolic flight in 16 s using a laboratory microfocus X-ray source. We demonstrate the operation of the device by analyzing the three-dimensional packing of particles (tomograms) and structure formation in a granular gas under periodic excitation (radiograms).},
author = {Torres Menendez, Harol and Heckel, Michael and Sack, Achim and Pöschel, Thorsten},
doi = {10.1063/1.5109622},
faupublication = {yes},
journal = {Review of Scientific Instruments},
note = {CRIS-Team Scopus Importer:2019-10-22},
peerreviewed = {unknown},
title = {{X}-ray tomography in micro-gravity},
volume = {90},
year = {2019}
}
@article{faucris.122140084,
abstract = {We report numerical evidence showing that periodic oscillations can produce unexpected and wide-ranging zig-zag parameter networks embedded in chaos in the control space of nonlinear systems. Such networks interconnect shrimplike windows of stable oscillations and are illustrated here for a tunnel diode, for an erbium-doped fiber-ring laser, and for the Hénon map, a proxy of certain CO lasers. Networks in maps can be studied without the need for solving differential equations. Tuning parameters along zig-zag networks allows one to continuously modify wave patterns without changing their chaotic or periodic nature. In addition, we report convenient parameter ranges where such networks can be detected experimentally. © 2013 American Physical Society.},
author = {Francke, Ricardo and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1103/PhysRevE.87.042907},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Zig}-zag networks of self-excited periodic oscillations in a tunnel diode and a fiber-ring laser},
volume = {87},
year = {2013}
}