Drops onto gradients of texture

¹  Physique et Mécanique des Milieux Hétérogènes, UMR 7636 du CNRS, ESPCI - 10 rue Vauquelin, 75005 Paris, France, EU
²  Laboratoire de Photonique et Nanostructures, UPR 20 du CNRS - Route de Nozay, 91460 Marcoussis, France, EU

Corresponding author: david.quere@espci.fr

Received: 20 May 2009
Accepted: 20 July 2009

Abstract

Hydrophobic microtextures on solids provide water repellency: drops hardly stick on these materials and bounce off after impacts. Here we achieved solids decorated with a texture of variable density. Impacting water drops were observed to bounce off obliquely, demonstrating a transfer of vertical momentum in the horizontal direction, after rebound. This allows us to understand why vibrated drops move on such surface: an asymmetric dewetting takes place for each cycle of the vibration, which leads to an incremental drift of the liquid towards regions of high texture density.