In this study, scattering processes of argon beam impinging on tungsten surface are investigated numerically by applying molecular dynamics (MD) simulations. Energy transfer, momentum change, and scattering processes of argon gas atoms from W(110) surface are discussed.
A new model of argon–tungsten (Ar–W) interaction is proposed. Based on the new proposed model, one can simplify the boundary conditions of this problem. The new boundary conditions are proved to be in line with previous experimental and theoretical results. This thesis demonstrates how to proceed normalization and further conversion of the MD simulation results into boundary conditions.
The newly proposed boundary conditions for Ar–W interactions have been utilized for numerical simulations of rarefied gas flow through nano-channels using the MD method. Taking into account that this method is very time consuming, we implemented all the simulations using CUDA capable Graphic Cards.
We found that the well-known and relatively simple Maxwell model of boundary conditions is able to reproduce gas flow through a tungsten channel with irregularities and roughness, while it results in a significant error in the case of a smooth metal surface. We further found that the flow rate through a relatively short channel correlates nonlinearly with the channel's length. This finding is in contrast with the results available in extant literature. Our results 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.

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