An equilibrium molecular-dynamics study was made of diffusion in random pore systems. The pore space was generated by using a simple percolation technique on a tessellation of three-dimensional space with periodic boundary conditions. Simulations were performed only for the percolating cluster. The substrate atoms were explicitly represented, and substrate-fluid and fluid-fluid interactions were modelled using Lennard-Jones potentials. Using this technique, results were obtained for an argon-in-graphite system having various porosities at 140K and a fluid density of 3.5kg/m3. The results clearly indicated that mass diffusion in completely random pore systems was different to that in the bulk phase.

Mass Diffusion of Atomic Fluids in Random Micropore Spaces using Equilibrium Molecular Dynamics. Biggs, M., Agarwal, P.: Physical Review A, 1992, 46[6], 3312-8