Numerical scheme for acoustic source term calculation in lighthills analogy

Tautz M, Besserer K, Hüppe A, Kaltenbacher M, Becker S (2015)

Publication Language: English

Publication Type: Conference contribution

Publication year: 2015

Conference Proceedings Title: Proceedings of the 22nd International Congress on Sound and Vibration

Event location: Florence IT

ISBN: 978-88-88942-48-3

Open Access Link: http://www.iiav.org/archives_icsv_last/2015_icsv22/content/papers/papers/full_paper_1223_20150315220804852.pdf

Abstract

In aeroacoustic simulations Lighthills analogy based on the Navier-Stokes equations is an estab- lished approach. It enables the computation of the acoustic pressure fluctuations by solving an inhomogeneous wave equation. The source term of this equation is calculated from an instation- ary flow field previously computed by a CFD solver. In the case of a low Mach number flow this CFD simulation can performed incompressible and the acoustic sources of the Lighthill equation can be simplified to contain only the laplacian of the fluid pressure. In this work a hybrid approach for this type of simulation was used. In the first step the incompressible Navier-Stokes equations were calculated by a finite volume solver. An instationary simulation was performed using a large eddy simulation turbulence model. Afterwards the laplacian of the pressure was calculated and interpolated onto a finite element mesh. In the second step a finite element code was used for the acoustic pressure computation. A Gauss scheme was implemented for the source term calculation. It used the face based dual mesh of the CFD mesh for the calculation of the first spatial derivative of the fluid pressure. Afterwards the laplacian was calculated on the initial CFD mesh. The first spatial derivative of the fluid pressure normal to the walls is zero and therefore the integral over all sources inside the domain has to be zero at each time step. This was taken into account during the calculation of the laplacian. As this approach was intended to perform aeroacoustic simulations of climatronic systems, it has been tested on a simplified outlet geometry. The results of the acoustic simulation were compared with experimental results and show good agreement with respect to noise level and modal excitation.

Authors with CRIS profile

Matthias Tautz Lehrstuhl für Prozessmaschinen und Anlagentechnik Kerstin Besserer Lehrstuhl für Prozessmaschinen und Anlagentechnik Stefan Becker Lehrstuhl für Prozessmaschinen und Anlagentechnik

Involved external institutions

Technische Universität Wien / Vienna University of Technology AT Austria (AT)

How to cite

APA:

Tautz, M., Besserer, K., Hüppe, A., Kaltenbacher, M., & Becker, S. (2015). Numerical scheme for acoustic source term calculation in lighthills analogy. In International Institute of Acoustics and Vibration (IIAV) (Eds.), Proceedings of the 22nd International Congress on Sound and Vibration. Florence, IT.

MLA:

Tautz, Matthias, et al. "Numerical scheme for acoustic source term calculation in lighthills analogy." Proceedings of the The 22nd International Congress on Sound and Vibration, Florence Ed. International Institute of Acoustics and Vibration (IIAV), 2015.

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