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Computational Study of Hypersonic Rarefied Gas Flow over Re-Entry Vehicles Using the Second-Order Boltzmann-Curtiss Constitutive Model

The aerothermodynamics of re-entry vehicles vary significantly upon re-entry, descent, and landing, because of the drastic changes in atmospheric density and velocity. In highly rarefied regimes, the conventional Navier-Stokes-Fourier equations may not provide an accurate prediction of aerothermodynamic loads acting on these vehicles. To tackle these challenges, an explicit mixed-type modal discontinuous Galerkin method was developed, based on the second-order Boltzmann-Curtiss constitutive model and the Maxwell slip and Smoluchowski jump conditions. A comprehensive analysis was conducted for different configurations of re-entry vehicles under various degrees of rarefaction. The computational results show that the rotational mode of energy transfer for diatomic gases substantially affects the lift-to-drag ratio and stability of re-entry vehicles. The total drag and heat transfer rate of the second-order constitutive model remained smaller than those of the first-order constitutive model in the rarefied regime, which makes the second-order results in better agreement with the direct simulation Monte Carlo.