格子Boltzmann守恒型非平衡态的外推边界

Conservative Non-equlibrium Extrapolation Boundary Condition in Lattice Boltzmann Method

摘要: 针对非平衡态外推边界处理方法在某些条件下发生质量泄漏的问题,结合质量守恒定律对其进行修正,建立一种新的质量守恒型的边界处理格式.其基本思想是在边界处定义一个虚拟密度来修正平衡态分布函数,使得系统质量守恒.以重力作用下的密度场及磁流体模拟问题为例,利用该格式进行分析,讨论质量泄露问题的本质及各种因素的影响.通过对三种典型的流动:二维Poiseuille流、Couette流、Womersley流的模拟,验证该边界格式的计算精度和稳定性.

Abstract: Removing mass leakage in non-equilibrium extrapolation method,a mass conservative boundary condition is proposed with improving non-equilibrium extrapolation method based on conservation of mass.Mass conservation of a system is ensured by defining an artificial density at solid boundary.Precision and stability of the new boundary condition are validated by simulating three classical flows (Poiseuille,Couette and Womersley).