Studies on argon collisions with smooth and rough tungsten surfaces

•We have studied argon beam–tungsten surface scattering by molecular-dynamics method.•We examined influence of roughness of surface on parameters of argon atoms after collision with it.•The mean kinetic energy of scattered atoms is almost independent of surface roughness.•It was shown that even small surface's irregularities transform gas-surface interactions to more diffusive-like. The aim of this work is to investigate argon scattering behaviors on the smooth and rough tungsten surfaces. Current work deals with numerical simulation of nanoscale heat transfer process accompanying with rarefied gas–solid substrate interactions using molecular dynamics (MD) method. Taking into account that this method is very time consuming, MD simulation using CUDA capable Graphic Cards is implemented. The results found that imperfection of the surface significantly influences on gas atom's momentum change upon collision. However, the energy exchange rate remains unchanged regardless to the surface roughness. This finding is in contrast with the results in extant literatures. We believed the results found in this paper are important for both numerical and theoretical analyses of rarefied gas flow in micro- and nano-systems where the choice of boundary conditions significantly influences flow.