Mechanisms in the size segregation of a binary granular mixture

Schröter M, Swinney HL, Ulrich S, Kreft J, Swift JB (2006)

Publication Language: English

Publication Status: Published

Publication Type: Journal article, Original article

Publication year: 2006


Publisher: American Physical Society

Book Volume: 74

Journal Issue: 1

DOI: 10.1103/PhysRevE.74.011307


A granular mixture of particles of two sizes that is shaken vertically will in most cases segregate. If the larger particles accumulate at the top of the sample, this is called the Brazil-nut effect (BNE); if they accumulate at the bottom, it is called the reverse Brazil-nut effect (RBNE). While this process is of great industrial importance in the handling of bulk solids, it is not well understood. In recent years ten different mechanisms have been suggested to explain when each type of segregation is observed. However, the dependence of the mechanisms on driving conditions and material parameters and hence their relative importance is largely unknown. In this paper we present experiments and simulations where both types of particles are made from the same material and shaken under low air pressure, which reduces the number of mechanisms to be considered to seven. We observe both BNE and RBNE by varying systematically the driving frequency and amplitude, diameter ratio, ratio of total volume of small to large particles, and overall sample volume. All our results can be explained by a combination of three mechanisms: a geometrical mechanism called void filling, transport of particles in sidewall-driven convection rolls, and thermal diffusion, a mechanism predicted by kinetic theory. (c) 2006 American Institute of Physics.

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Schröter, M., Swinney, H.L., Ulrich, S., Kreft, J., & Swift, J.B. (2006). Mechanisms in the size segregation of a binary granular mixture. Physical Review E, 74(1).


Schröter, Matthias, et al. "Mechanisms in the size segregation of a binary granular mixture." Physical Review E 74.1 (2006).

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