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

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.