Comparison of Chemical Reaction Models with Various Experimental Reentry Capsules Using DSMC

Abstract

Direct simulation Monte Carlo (DSMC) [1] is a particle method that is used to study transition and near-continuum complex flows. In DSMC, every particle represents a large number of real molecules. The DSMC algorithm can be summarized as a sequence of movement and collision phases. Particles are moved in a straight trajectory in the movement phase. This is succeeded by intra-cell probabilistic collisions. Post-collision velocities are chosen to preserve momentum and energy and ensure that the correct viscosity is obtained. In order to obtain realistic results, the cell size should be a fraction of the local mean free path, and the time step should be a fraction of the mean collision time. The rotational and vibrational energy exchange during collisions is computed using the Larsen-Borgnakke (LB) [1] method. Chemical reactions are implemented in DSMC using phenomenological algorithms such as the Total Collision Energy (TCE) and the Quantum-Kinetic (QK) [2] model.