AN IMPROVED INCOMPRESSIBLE LATTICE BOLTZMANN MODEL FOR TIME-INDEPENDENT FLOWS

It is well known that the lattice Boltzmann equation method (LBE) can model the incompressible Navier-Stokes (NS) equations in the limit whe re density goes to a constant. In a LBE simulation, however, the densi ty cannot be constant because pressure is equal to density times the s quare of sound speed, hence a compressibility error seems inevitable f or the LBE to model incompressible flows. This work uses a modified eq uilibrium distribution and a modified velocity to construct an LBE whi ch models time-independent (steady) incompressible flows with signific antly reduced compressibility error. Computational results in 2D cavit y flow and in a 2D flow with an exact solution are reported.