LATTICE BOLTZMANN SIMULATION OF A 2D BACKWARD FACING STEP AT LOW TO MODERATE REYNOLDS NUMBER: A COMPARISON OF THE STABIL- ITY OF BGK AND TRT COLLISION OPERATORS
Palavras-chave:
backward-facing step, Lattice-Boltzmann Method, stability, two-relaxation time operator, Bhatnagar-Gross-Krook operatorResumo
In this study we present Lattice-Boltzmann simulations of a 2D backward facing step flow in
the low to moderate Reynolds number range. A single relaxation time model for the collision operator
(BGK) is compared to a two-relaxation-time model (TRT) and 3-D experiments of [Tihon, J., Penkakova,
V. and Pantzali, M., 2010. The effect of inlet pulsations on the backward- facing step flow. European
Journal of Mechanics B-Fluid, Vol. 29, pp. 224-235]. Special attention is devoted to detachment and
reattachment locations along the line of center of the computational domain, and to numerical stability
comparison between BGK and TRT as a function of grid resolution for similar accuracy. A traditional
finite volume method is also implemented for comparison. Results show that the BGK implementation
achieves similar accuracy at lower grid resolution, maintaining numerical stability of the method at re-
duced computational cost. BGK and TRT implementations agree with experiments and the finite volume
method at Reynolds number of 590.
