Molecular Dynamics Study on the Effects of In-Plane Pore Oscillations on Flow through Nanoporous 2D Membranes

Although extensive studies have been performed into the use of nanoporous 2D membranes for filtration, most have focused on static and quasi-equilibrium behavior. Many natural and practical systems, however, involve dynamic coupling between the fluid and the material through which the fluid flows. This requires understanding the physical mechanisms that arise in nonequilibrium mechano-nanofluidic systems. In this work, we first develop the necessary theoretical foundation to perform fundamental studies of nanofluidic dynamic behavior that seclude the effects of adding arbitrary heat into the system. Then we use Molecular Dynamics (MD) to analyze the effects of in-plane harmonic pore oscillations on water transport through nanoporous and subnanoporous graphene. We report an increase in average axial velocity and a decrease in average water density inside the pore. The relative competition between these effects determines the degree to which flux through the membrane is enhanced, and flux enhancement occurs for all the considered oscillatory schemes in comparison to the static case. We use hydrodynamic models and analysis of nanoscopic behavior to explain the observed phenomena as a result of dynamic coupling between the membrane and the fluid.