Attention was focusessed on identifying the main microscopic processes that influenced the Soret effect in a fluid mixture confined in an uncorrugated slit pore. A boundary driven non-equilibrium molecular dynamics scheme was applied to binary mixtures of super-critical Lennard-Jones spheres representing methane and n-decane. Following previous work, a systematic study was made of the influence of the parameters used to describe a model slit pore on an effective thermal diffusion factor. Among these parameters were the nature of the reflection of the diffusing particles at the walls (specular or diffusive), the pore width with respect to the particle size and the fluid-wall potential strength. Simulations were run both on equimolar and non-equimolar mixtures. The results indicated that thermal diffusion was effectively lowered only for strong fluid-wall interactions. It was shown that the general trends, which were different under sub- and super-critical conditions, could be explained by a careful analysis of the relative sorption energies of the two compounds.

Thermal Diffusion in Micropores by Molecular Dynamics Computer Simulations. Galliéro, G., Colombani, J., Bopp, P.A., Duguay, B., Caltagirone, J.P., Montel, F.: Physica A, 2006, 361[2], 494-510