COMPARISONS BETWEEN MONTE-CARLO METHODS AND NAVIER-STOKES EQUATIONS FOR REENTRY FLOWS

A detailed comparison is made between Navier-Stokes and direct stimula tion Monte Carlo calculations for flows near the continuum limit to as sess the accuracy of the continuum equations in this regime. Meaningfu l comparisons require the use of similar physical models. This necessi tates the inclusion of a separate rotational energy equation and use o f slip boundary conditions. Inclusion of slip boundary conditions resu lted in improved agreement between surface properties. Moreover, good agreement was obtained for the various temperatures in the nonequilibr ium portion of the flowfield that does not contain the shock region. D epartures are noted in the shock region and in regions where thermal d iffusion effects are important.