A direct relaxation process for particle methods in gas-kinetic theory

The multi-scale flow mechanism is crucial for force and heat loaded on near-space reentry vehicles, the control of spacecraft by thrusters, propelling cooling MEMS, etc. Since continuum rarefied often exist simultaneously, modeling prediction such a field very complicated. One important efficient way predicting constructing numerical methods adapting properties temporal integral solutions (or equivalent characteristic line solutions) model equations in gas-kinetic theory. can be classified into FP-type BGK-type, have deterministic form or stochastic particle form. these are strictly based equations, they also restricted equations. difficulty complexity equation that has complete asymptotic preserving property gas mixture with non-equilibrium internal energy will prevent further extension methods. Therefore, this paper addresses question whether method established not but directly adapts relaxation rates macroscopic variables as stress flux. algorithm BGK-type clear simple, its collision step modified work, where firstly evolve according to their rates, then molecules participate inter-molecular collisions get after-collision velocities from after-evolution variables. direct process does depend anymore. Finally, validity accuracy examined five test cases.