Europhys. Lett.
Volume 74, Number 2, April 2006
Page(s) 215 - 221
Section General
Published online 22 March 2006
Europhys. Lett., 74 (2), pp. 215-221 (2006)
DOI: 10.1209/epl/i2005-10535-x

Grad's approximation for missing data in lattice Boltzmann simulations

S. S. Chikatamarla1, S. Ansumali2 and I. V. Karlin1

1  Aerothermochemistry and Combustion Systems Laboratory, ETH Zurich CH-8092 Zürich, Switzerland
2  School of Chemical and Biomedical Engineering, Nanyang Technological University 639798 Singapore

received 24 October 2005; accepted in final form 27 February 2006
published online 22 March 2006

Engineering applications of computational fluid dynamics typically require specification of the boundary conditions at the inlet and at the outlet. It is known that the accuracy and stability of simulations is greatly influenced by the boundary conditions even at moderate Reynolds numbers. In this paper, we derive a new outflow boundary condition for the lattice Boltzmann simulations from non-equilibrium thermodynamics and Grad's moment closure. The proposed boundary condition is validated with a three-dimensional simulation of a backward facing step flow. Results demonstrate that the new outlet condition significantly extends the simulation capability of the lattice Boltzmann method.

05.20.Dd - Kinetic theory.
47.11.-j - Computational methods in fluid dynamics.

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