Assessment of Gas-Surface Interaction Models for Computation of Rarefied Hypersonic Flows

Among the few classes of computational approaches for examining rarefied gas dynamics, the most widely used technique for spatial scales relevant to suborbital spaceflight is the direct simulationMonte Carlo method. One area in which the direct simulation Monte Carlo method can be improved is the numerical modeling of the interactions between gas molecules and solid surfaces. Gas–surface interactions are not well understood for rarefied hypersonic conditions, although various models have been developed. The goal of this study is the assessment of gas–surface interaction models in use with the direct simulation Monte Carlo method. Assessment is made of the two most common gas–surface interaction models in use with direct simulation Monte Carlo: the Maxwell model and the Cercignani, Lampis, and Lord model. The assessment is performed by simulations of flat-plate wind-tunnel tests. Boundary-layer profiles are compared with existing wind-tunnel data. At about 90 % accommodation, both models match the wind-tunnel profiles. Parametric studies demonstrate differences between the model predictions of scattering distributions, boundary-layer profiles, and surface-property distributions. The two models offer similar performance for computing flat-plate aerodynamics. Nomenclature aQ = accommodation coefficient of molecular property Q Cf = skin-friction coefficient w=q