The collision consistency of lattice-BGK model for simulating rarified   gas flows in microchannels
  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. 
Chun Zou, Zhi-Wei Tian, Hong-Juan Liu and Chu-Guang Zheng