Modeling and simulations for molecular scale hydrodynamics of the moving contact line inimmiscible two-phase flows

Abstract

This paper starts with an introduction to the Onsager principle of minimum energydissipation which governs the optimal paths of deviation and restoration to equilibrium.Then there is a review of the variational approach to moving contact line hydrodynamics.To demonstrate the validity of our continuum hydrodynamic model, numerical results frommodel calculations and molecular dynamics simulations are presented for immiscibleCouette and Poiseuille flows past homogeneous solid surfaces, with remarkableoverall agreement. Our continuum model is also used to study the contact linemotion on surfaces patterned with stripes of different contact angles (i.e. surfaces ofvarying wettability). Continuum calculations predict the stick–slip motion forcontact lines moving along these patterned surfaces, in quantitative agreement withmolecular dynamics simulation results. This periodic motion is tunable throughpattern period (geometry) and contrast in wetting property (chemistry). Theconsequence of stick–slip contact line motion on energy dissipation is discussed.