Drag and thermophoresis on a sphere in a rarefied gas based on the Cercignani-Lampis model of gas-surface interaction

TL;DR

This paper investigates how different gas-surface interaction models, specifically the Cercignani-Lampis model, affect the viscous drag and thermophoresis forces on a sphere in a rarefied gas across various flow regimes.

Contribution

It introduces a kinetic model approach using the Cercignani-Lampis scattering kernel to analyze gas-surface interactions in rarefied gas flows around a sphere.

Findings

Drag and thermophoresis forces vary significantly with gas-surface interaction parameters.

The model covers free molecular to continuum flow regimes.

Results highlight the importance of accommodation coefficients in force calculations.

Abstract

The influence of the gas-surface interaction law on the classical problems of viscous drag and thermophoresis on a spherical particle with high thermal conductivity immersed in a monatomic rarefied gas is investigated on the basis of the solution of a kinetic model to the linearized Boltzmann equation. The scattering kernel proposed by Cercignani and Lampis is employed to model the gas-surface interaction law via the setting of two accommodation coefficients, namely the tangential momentum accommodation coefficient (TMAC) and the normal energy accommodation coefficient (NEAC). The viscous drag and thermophoretic forces acting on the sphere are calculated in a wide range of the rarefaction parameter, which is defined as the ratio of the sphere radius to an equivalent free path of gaseous particles, so that the free molecular, transition and continuum regimes of the gas flow are covered.