A gas-surface interaction kernel for diatomic rarefied gas flows based on the Cercignani-Lampis-Lord model

This work presents a kinetic wall boundary model for diatomic gas molecules. The model is derived by generalizing the Cercignani-Lampis-Lord gas-surface interaction kernel in order to account for the gas internal degrees of freedom. Here, opposed to the extensions by Lord [“Some extensions to the Cercignani-Lampis gas-surface scattering kernel,” Phys. Fluids 3, 706–710 (1991)], energy exchange between different molecular modes is honored and thus, different physical phenomena arising from inelastic gas–surface collisions can be described. For practical implementations of the model, a Monte–Carlo algorithm was devised, which significantly reduces the computational cost associated with sampling. Comparisons of model predictions with experimental and molecular dynamics data exhibit good agreement. Moreover, simulation studies are performed to demonstrate how energy transfers between different modes due to wall collisions can be exploited for gas separation.