Next-generation CFD for hypersonic and aerothermal flows

In this paper, we discuss the current status of computational fluid dynamics for hypersonic aerodynamics, supersonic combustion, and aerothermodynamics. These flows are characterized by high temperatures, finite-rate chemical reactions, transition, turbulence, and gas-surface interactions. Large-scale computation is making it possible to resolve a larger range of length and time scales, as well as increase the complexity of the physical models. However, the results of these simulations remain remarkably sensitive to the numerical methods and the quality of the computational grid. Furthermore, many of the models required to represent important physical processes at relevant conditions remain uncertain. For example, turbulence models developed for canonical incompressible flows are used with little to no modification under highly compressible conditions. Turbulent combustion models that were developed for nearly constant pressure and high reaction rates are applied at supersonic conditions where these assumptions are not valid. Thus, next-generation computers will reduce solution times and increase simulation complexity, but investments need to made in the development of more reliable numerical methods and improved physical models for hypersonic and aerothermal flows.