Closely coupled DSMC hypersonic reentry flow simulations with photon monte carlo radiation

Earth re-entering spacecrafts traveling at high Mach number generate a strong shock layer ahead of the blunt body with a high temperature above 60,000 K. These extreme Mach number and temperature flows are sufficiently energetic to initiate gas ionization and thermo-chemical ablation processes. The nonequilibrium energy distribution of atoms and molecules in air causes significant radiative energy that can add or remove energy from the flowfield. To perform accurate and efficient analyses of chemically reacting flowfield - radiation interactions in hypersonic nonequilibrium flows the direct simulation Monte Carlo (DSMC) and photon Monte Carlo (PMC) methods were used to simulate flowfield - radiation coupling of Stardust reentry flows at near continuum regime altitudes. We perform closely coupled DSMC - PMC simulations using a ray tracing schemes of photon bundles that travel through the same DSMC computational cell and with small statistical error. The radiative heat source calculated by the PMC method is then transfered to flowfieid which influenced by the add or removal of radiative energy as calculated by the PMC. For these near continuum flow regimes, the radiation was found to influence the flowfield. The high radiative energy leads to a decrease in both heavy particle translational and internal temperature in the shock layer and a decrease in the convective heat flux to the Stardust body. The DSMC - PMC coupled simulations are performed until both the flow and radiation fields are converged.