Investigation of Benard, taylor and thermal stress instabilities in rarefied gases by Direct Simulation Monte Carlo method

Thermal (Benard and thermal stress) and rotational (Taylor) instabilities in a rarefied gas are investigated by Direct Simulation Monte Carlo (DSMC) method. Particular emphasis is given to the numerical aspects of DSMC (accuracy, convergence etc.) that were not investigated in the previous studies and to the refining of the simulation results by using special data processing (filtering) procedure. In the stratified rarefied gases with high temperature gradients the Boussinesq approximation is not valid and it is shown that onset of instabilities in the non-Boussinesq fluid (rarefied gas) is not determined by a single non-dimensional parameter (Rayleigh or Taylor number). Thermal (Benard and thermal stress) instabilities in the stratified rarefied gas are analyzed in different geometries including the case with curvilinear boundaries.