Comparison of Multicomponent Diffusion and Thermochemical Nonequilibrium Modeling Effects in CFD and DSMC

Computational fluid dynamics (CFD) simulations of hypersonic flow over a 10 cm cylinder at altitudes ranging from 40 to 85 km are presented. Simulations are run with multicomponent species diffusion governed by the Stefan-Maxwell equations as well as with the recently updated Modified Marrone-Treanor thermochemical nonequilibrium model for five species air. Results are compared against the current state of the practice for diffusion and thermochemical nonequilibrium modeling. At each altitude the local gradient length Knudsen number is used to identify regions of the flow that are continuum, near continuum, and rarefied. Altitudes that are representative of these regimes are then simulated with the direct simulation Monte Carlo (DSMC) method and compared to the CFD results.