Stress dependent slip boundary condition for single-and two-phase fluid flow on a substrate

摘要

In problems such as moving contact line and corner flows, fluid velocity adjacent to the wall varies spatially in direction normal and tangential to the wall. Navier and Maxwell slip models considered flows where velocity only changed in the wall normal direction. In this paper, molecular dynamics simulation is used to study the moving contact line problem. In the vicinity of the triple contact point, slip length is shown to be dependent on the local velocity gradient tensor and number density. Scaling for slip length and the velocity gradient tensor is identified; that helps collapse the data to give a universal curve for slip length. The universal curve helps relate slip length to the fluid-wall properties and the local flow parameters. Generalized slip model together with the universal curve, provide an accurate boundary condition for a wide range of steady flow problems without having to perform computationally expensive molecular dynamics simulations.