Depinning of three-dimensional drops from wettability defects

Substrate defects crucially influence the onset of sliding drop motion under lateral driving. A finite force is necessary to overcome the pinning influence even of microscale heterogeneities. The depinning dynamics of three-dimensional drops is studied for hydrophilic and hydrophobic wettability defects using a long-wave evolution equation for the film thickness profile. The model is studied employing effective algorithms for the parameter continuation of pinned steady drops and for the time simulation of the dynamics of sliding drops that perform a stick-slip motion. The discussion focuses on common features and significant differences of the depinning process for three-dimensional and two-dimensional drops. Copyright (C) EPLA, 2009