Diffusion of methane in a mica slit pore: Molecular dynamics simulations and correlation models

Equilibrium molecular dynamics simulations have been used to calculate the self-diffusion coefficients of fluid methane confined in mica slit pore at different temperatures, densities and pore widths. On the other hand, based on the Chapman-Enskog theory and Heyes relationships, two simple correlation models which can describe the self-diffusion coefficient of fluid methane in mica slit pore are proposed as a function of the temperature, density and pore width. Both models are written in terms of Lennard-Jones (LJ) dimensionless variables, which are defined in terms of the LJ parameters σ and ε. These parameters are meaningful at molecular level. The validity of these models is evaluated by comparing with the calculated self-diffusion coefficient data at different state points. The average error of both these two models is usually less than 13%