Multiscale modeling and simulation of dynamic wetting

Abstract

In this paper, we present a multiscale analysis on dynamic wetting and liquid droplet spreading on solid substrates. In the proposed multiscale dynamic wetting model, we couple molecular scale adhesive interaction (the van der Waals type force) and the macroscale flow – that is: we combine a coarse-grain adhesive contact model with a modified Gurtin–Murdoch surface elasto-dynamics theory to formulate a multiscale moving contact line theory to simulate dynamic wetting. The advantage of adopting the coarse grain adhesive contact model in the moving contact line theory is that it can levitate and separate the liquid droplet with the solid substrate, so that the proposed multiscale moving contact line theory avoids imposing the non-slip condition, and then it removes the subsequent singularity problem, which allows the surface energy difference and surface stress propelling droplet spreading naturally.By employing the proposed method, we have successfully simulated droplet spreading over various elastic substrates. The obtained numerical simulation results compare well with the experimental and molecular dynamics results reported in the literature.