The collision consistency of lattice-BGK model for simulating rarified gas flows in microchannels

TL;DR

This paper investigates the collision consistency condition in the lattice-BGK model for simulating rarefied microchannel gas flows, demonstrating that maintaining tau=1.0 significantly improves simulation accuracy over non-consistent approaches.

Contribution

It introduces the concept of collision consistency in the lattice-BGK model and shows its importance for accurately simulating microflows where continuum assumptions break down.

Findings

Collision consistency tau=1.0 yields highly accurate microchannel flow simulations.

Simulations with collision consistency match analytical solutions closely.

Non-consistent simulations are less accurate by three or four orders of magnitude.

Abstract

The collision consistency between the BGK collision model equation and lattice-BGK (LBGK) model is proposed by researching the physical significance of the relaxation factor tau in LBGK model. For microscalar flow in which the continuum hypothesis is not still satisfied, the collision consistency tau=1.0 should be ensured when using the LBGK model for simulating microflows. The results of simulating microchannel Poiseuille flow with constant pressure gradient under collision consistency by using LBGK model are well consistent with the analytical solutions, and the accuracy of these results is three or four orders of magnitude higher than those that don't satisfy the collision consistency.