Osmotic and diffusio-osmotic flow generation at high solute concentration. II. Molecular dynamics simulations

摘要

In this paper, we explore osmotic transport by means of molecular dynamics(MD) simulations. We first consider osmosis through a membrane, and investigatethe reflection coefficient of an imperfectly semi-permeable membrane, in thedilute and high concentration regimes. We then explore the diffusion-osmoticflow of a solute-solvent fluid adjacent to a solid surface, driven by achemical potential gradient parallel to the surface. We propose a novelnon-equilibrium MD (NEMD) methodology to simulate diffusion-osmosis, byimposing an external force on every particle, which properly mimics thechemical potential gradient on the solute in spite of the periodic boundaryconditions. This NEMD method is validated theoretically on the basis oflinear-response theory by matching the mobility with their Green-Kuboexpressions. Finally, we apply the framework to more realistic systems, namelya water-ethanol mixture in contact with a silica or a graphene surface.