科研成果详情

The discrete velocity based Lattice Boltzmann method forms a well defined hierarchy which can exactly recover the essential hydrodynamics in the macroscopic level. Conventional LB models, owing to their low order approximation of the continuum Boltzmann kinetic equation, are limited to simulation of flow in the low Mach number, nearly incompressible regime. High order LB models can be directly obtained through a systematic discretization of the Boltzmann kinetic equation11. Based on a moment expansion approach, the velocity distributions can be decomposed into higher order Hermite polynomials and the resulting expansion coefficients are the hydrodynamics moments. Such high order LB model is able to recover the high order hydrodynamics moments precisely to conserve the mass, moments and energy; however it is still facing instability problems when the local flow Mach number is high. In this study, a 39 state LB model is presented and coupled with a scalar energy equation for solving conservation of mass, momentum and energy in a fluid system. This hybrid approach is able to increase simulation Mach number substantially for compressible viscous flows. The validation results compare well with N-S (Navier-Stokes) equations based prediction for a two dimensional convergence-divergence nozzle case, three dimensional simulation of a Mach 0.5 DLR-F4 aircraft also shows favorable agreements with experimental measurement. Copyright © 2009 by Yanbing Li,Xiaowen Shan.