Nonequilibrium Molecular Dynamics Simulations of Coupled Heat and Mass Transport in Binary Fluid Mixtures in Pores

Molecular dynamics simulations were carried out for a binary fluid mixture in a slit pore. The fluid was an argon-like Lennard–Jones/spline model. The pore wall was represented by the Steele model for a layered graphite structure. The pore had a heat source in one end and a heat sink in the other, resulting in a lateral temperature gradient, a Soret effect, and a thermal creep flow along the pore wall. Potential models with various depths were used to examine the effect of wetting and adsorption on the thermal creep flow. The main results were as follows, (a) A relatively strong creep flow was generated parallel to the wall by the temperature gradient. For strongly attracting fluid–wall potentials, the flow occurred from the cold to the hot end of the pore near the wall (except for the very narrow pore) and oppositely in the center of the pore. For a purely repulsive potential, the flow was weak and mostly in the opposite direction, (b) The thermal diffusion coefficient was comparable to that in bulk fluid at the same overall density, except when the creep flow was strong, in which case the thermal diffusion was blurred by the convective mixing.