Approximate two layer (inviscid/viscous) methods to model aerothermodynamic environments

Aeroassisted orbital transfer vehicles (AOTVs) and HSTs fly hypersonically at altitudes higher than those of Apollo and Space Shuttle type, whose flowfield could be considered a continuum with insignificant chemical nonequilibrium effects; AOTVs and HSTs will by contrast fly in the transitional regime between continuum and free molecule flow, where chemical nonequilibrium within the shock layer can be significant. Attention is presently given to the numerical and approximate methods of hypersonic flowfield calculation, emphasizing the role of aerodynamic heating. The development status of boundary layer methods, fully viscous methods, and gas models is evaluated.