Equilibrium Molecular Dynamics Computer Simulations of the Transport Coefficients of Ar-CH4Mixtures

Abstract

Abstract Equilibrium molecular dynamics computer simulations have been used to determine the transport coefficients of model Ar-CH4 mixtures at state points for which experimental data are available. Both species are represented by single-site Lennard-Jones pair potentials with Lorentz-Berthelot rules for the cross-species interactions. We calculate the self-diffusion coefficients for each species and also mutual-diffusion coefficients using time correlation functions in the Green-Kubo formulae and mean square displacements. Time correlation functions are used to evaluate the shear and bulk moduli and viscosities, thermal conductivity and the thermal diffusion coefficient in [NVE] and [NVT] ensembles. Only for the bulk viscosity is there a significant ensemble dependence. In order to evaluate the thermo-transport coefficients, we use a rigorous definition for the heat flux, which includes the partial enthalpy of the two species. This was obtained from separate computations carried out at constant pressure...