DSMC Implementation of the Schamberg Model: Comparison with the Maxwell Model

摘要

In order to provide a further tool for the evaluation of the molecule-surface interaction and therefore of the aerodynamic forces from a Direct Simulation Monte Carlo (DSMC) code, a DSMC implementation of the Schamberg model is proposed. This model has been considered of interest; it seems to be more realistic, from a phenomenological point of view, compared with the Maxwell model. In fact, unlike the Maxwell model, the Schamberg model does not separate the re-emission phase into a "specular" and a "diffusive" interaction, but the re-emission includes, at the same time, both phases; this model is denoted "quasi-specular". The capability of convergence of aerodynamic coefficients to the theoretical values in terms of the number of molecule-surface collisions and of the free stream parameters has been taken as a worth index. The results are compared also with those from the DSMC implementation of the Maxwell model. Runs are made on a flat plate, at test conditions met by a capsule during the re-entry in the altitude interval 60–100 km and at the extreme molecule-surface interactions: diffusive fully accommodate and specular. Unfortunately the results showed that the proposed implementation is unsuccessful or even that the Schamberg model is unsuitable for the DSMC method.