Application of poly-Gaussian random processes to flow model near rough surface in rarefied gas

Abstract

The properties of poly-Gaussian model of randomly rough surface are investigated affecting its aerodynamic characteristics in rarefied gas flow. The representation of probability distribution in the form of the mixture of Gaussian distributions allows to derive analytic expressions of factorial moments of the number of outliers upon a level, playing a key role in finding the scattering function of gas atoms on the surface and the momentum exchange coefficients. The important particular case of poly-Gaussian processes in considered - spherically-symmetric random processes, permitting to simplify the conditions. The asymptotic evaluations are found for high level crossings characteristics corresponding to the case of weakly rough surface. Obtained results allow to evaluate the influence of surface roughness on the type of gas flow near the surface in comparison to Gaussian model of roughness.

Keywords:

rarefied gas flow, gas-surface interaction, poly-Gaussian model of roughness