GASEOUS FLOWS IN MICRO-CHANNELS: A NUMERICAL STUDY USING MESOSCOPIC LATTICE BOLTZMANN METHOD
The current work implements the Two-Relaxation time
(TRT) model of Lattice Boltzmann Method (LBM) to compute
rarefied gaseous flows in an infinitely long (periodic) microchannel. Significant focus has been given to slip and transition regimes, as the Knudsen layer in the latter has to be captured for accurate prediction of flows. With a plethora of approaches available in the literature to model the non-linear velocity variation in this layer, a simple approach using the Bosanquet-type effective viscosity has been employed. Further, standard bounce-back boundary conditions have been implemented over the channel walls, which are computationally simple over the combined bounce-back/diffusive and specular reflections. This has been achieved by tuning the anti-symmetrical relaxation time
to achieve second-order slip boundary conditions at the channel walls. Good agreement of the results (velocity profiles and Knudsen minimum characteristic curve) obtained from the current model with the literature is observed, which establishes TRTLBM to be a useful numerical tool for computing micro-flows.