The influence of gas-wall interactions on the accommodation coefficients for rarefied gases:a molecular dynamics study

The energy accommodation coefficient (EAC) and the momentum accommodation coefficient (MAC) are two significant parameters determining the gas-solid energy and momentum exchange efficiencies. In this work,\u3cbr/\u3emolecular dynamics (MD) simulations were employed to study the impact of gas-wall interaction potential on energy and momentum accommodation coefficients between Gold and monoatomic gases (Argon and\u3cbr/\u3eHelium). The MD simulation setup consists of two infinite parallel plates of unequal temperature positioned at certain distance (12 nm and 102 nm for Argon and Helium gases, respectively) apart from each other, and\u3cbr/\u3eof gas molecules confined between them. A pairwise Lennard-Jones 12-6 potential was considered at the solid-gas interface. The interaction potential parameters were obtained using the Lorentz-Berthelot (LB) and Fender-\u3cbr/\u3eHalsey (FH) mixing rules, as well as based on existing ab-initio computations. Comparing the obtained results for the accommodation coefficients with empirical values revealed that the interaction potential based on abinitio\u3cbr/\u3ecalculations is the most reliable one for computing ACs. Besides, in the case of Au-Ar, the LB mixing rule substantially overpredicts the potential well depth which leads to sticking gas atoms on the solid surface. As a result, computing accommodation coefficients in this case from numerical point of view was not possible