G607 Numerical simulation of flow in high Reynolds number region using quasi-equilibrium lattice Boltzmann model : Effect of the ratio of bulk viscosity to kinematic viscosity

Abstract

Quasi-equilibrium Lattice Boltzmann model (QELBM) has been developed in order to get stable solution at high Reynolds number flow simulation by tuning viscosity ratio, namely, the ratio of bulk viscosity and kinematic viscosity. QELBM uses only two relaxation times and does not need to solve non-linear equation at each grid point to enhance stability, thus the algorithm is simpler than Multi-Relaxation Time model and Entropic Lattice Boltzmann model. However, there is degree of freedom for determining the viscosity ratio and the effect of viscosity ratio on the results has not been known yet. In this study, we investigate the region of viscosity ratio where the calculation becomes stable and the effect of viscosity ratio on flow field in various Reynolds numbers and Mach numbers.