Zonally decoupled direct simulation Monte Carlo solutions of hypersonic blunt-body wake flows

Direct simulation Monte Carlo (DSMC) solutions are presented for the hypersonic flow behind a blunt body in which the wake region is solved in a zonally decoupled manner. The forebody flow is solved separately using either a DSMC or a Navier-Stokes method, and the forebody exit-plane solution is specified as the inflow condition to the decoupled DSMC solution of the wake region. Results are presented for a 70-deg, blunted cone at flow conditions that can be accommodated in existing low-density wind tunnels with the Knudsen number (based on the base diameter) ranging from 0.03 to 0.001. The zonally decoupled solutions show good agreement with fully coupled DSMC solutions of the wake flow densities and velocities. The wake closure predicted by the zonally decoupled solutions is in better agreement with fully coupled results than that predicted by a fully coupled Navier-Stokes method, indicating the need to account for rarefaction in the wake for the cases considered. The combined use of Navier-Stokes for the forebody with a decoupled DSMC solution for the wake provides an efficient method for solving transitional blunt-body flows where the forebody flow is continuum and the wake is rarefied. (Author)