QUASIEQUILIBRIUM LATTICE BOLTZMANN MODELS WITH TUNABLE PRANDTL NUMBER FOR INCOMPRESSIBLE HYDRODYNAMICS

Recently, it was shown that energy conserving (EC) lattice Boltzmann (LB) model is more accurate than athermal LB model for high-resolution simulations of athermal flows. However, in the sub-grid (SG) domain, the behavior is found to be opposite. In this work, we show that via multi-relaxation model, it is possible to preserve the accuracy of the EC LB for both SG and direct numerical simulation (DNS) models. We show that by introducing a nonunit Prandtl number, under-resolved simulations can also be performed quite efficiently, a property which we attribute to the enhanced sound-relaxation.