Coexistence of two singularities in dewetting flows: regularizing the corner tip.
Entrainment in wetting and dewetting flows often occurs through the formation of a corner with a very sharp tip. This corner singularity comes on top of the divergence of viscous stress near the contact line, which is only regularized at molecular scales. We investigate the fine structure of corners appearing at the rear of sliding drops. Experiments reveal a sudden decrease of tip radius, down to 20 microm, before entrainment occurs. We propose a lubrication model for this phenomenon, which compares well to experiments. Despite the disparity of length scales, it turns out that the tip size is set by the classical viscous singularity, for which we deduce a nanometric length from our macroscopic measurements.
Laboratoire Matière et Systèmes Complexes, UMR CNRS 7057, Université Paris Diderot, 10 rue Alice Domon et Léonie Duquet, 75205 Paris cedex 13, France.
Ivo
I
Peters
Jacco H
JH
Snoeijer
Adrian
A
Daerr
Laurent
L
Limat