Depinning of 2d and 3d Droplets Blocked by a Hydrophobic Defect

Abstract

On non-ideal real substrates the onset of droplet motion under lateral driving is strongly influenced by substrate defects. A finite driving force is necessary to overcome the pinning influence of microscale heterogeneities. The dynamics of depinning two- and three-dimensional droplets is studied using a long-wave evolution equation for the film thickness profile in the case of a localized hydrophobic wettability defect. It is found that the nature of the depinning transition explains the experimentally observed stick-slip motion.