Molecular dynamics simulations on the scattering of heavy gases on the composite surfaces

S Yousefi-Nasab and J Safdari and J Karimi-Sabet and MH Mallah, VACUUM, 183, 109864 (2021).

DOI: 10.1016/j.vacuum.2020.109864

Cercignani-Lampis-Lord (CLL) is a boundary condition used in the DSMC method, due to the use of tangential and normal momentum accommodation coefficients (TMAC and NMAC) extractable by Molecular Dynamics (MD) simulations or experimental platforms, the accuracy of this boundary condition is by up to 15% relative to diffuse model (Mehta et al., 2014) 1. These coefficients in slip, transitional, and free molecular flow regimes takes a value other than the unit. Since the temperature and velocity of the molecules after their scattering from the surface in the CLL model, drag coefficient, slip velocity, shear stress, and jumping temperature is completely dependent on the values of these coefficients, it is very important to determine these coefficients for different gases and surfaces. In this paper, first the DGEBA-TETA/carbon composite was simulated with MD method using an efficient algorithm and then using this method shown that in the interaction of heavy gases such as uranium, tellurium and sulfur hexafluoride with a composite surface, TMAC and NMAC were strongly dependent on Knudsen number and temperature of gases, velocity and temperature of composite, and the dependency of the TMAC was less than the NMAC for different conditions of gas characteristics. In these cases, tellurium hexafluoride had the greatest impact.

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