HYPERSONIC RAREFIED FLOW PAST SPHERES INCLUDING WAKE STRUCTURE

Results of a numerical study using the direct simulation Monte Carlo m ethod are presented for hypersonic rarefied now past spheres. The flow conditions considered are those corresponding to low-density wind-tun nel test conditions. The set of the experimental conditions for the ca lculations encompasses the transitional to near-continuum now regimes. Comparison of the calculated drag with experimental results shows goo d agreement to well within the experimental error Particular attention is focused on the wake structure. Calculations show that the wake is very rarefied with considerable thermal nonequilibrium for all the cas es considered. No now separation is observed in the wake for the near- continuum case where a vortex has been predicted by Navier-Stokes-type calculations.