Séminaires MSC
"Matière et Systèmes Complexes"
                      
Lundi 16 janvier 2006 à 11h30
Tour 33, couloir 33-43, 2ème étage, salle de réunion

Jacco Snoeijer
(MSC, Université Paris 7)

Forced wetting transitions: from singular drops to the Landau-Levich problem

Everyday life wetting and dewetting phenomena, such as drops sliding down a window, still form a fundamental problem: classical hydrodynamics fails to describe the contact line area that separates wet from dry areas. In this talk we discuss experimental and theoretical results on "forced wetting transitions" at which contact lines give way to liquid entrainment. First, we address the wetting of a hydrophobic plate that is withdrawn from a bath of liquid at high velocity. In contrast with previous theories, this transition is governed by an overhanging ridge that spontaneously starts to climb out of the bath. We then consider drops sliding down an inclined plane. These display singular shapes before breaking up into smaller drops, and we analyze the 3D flow near the singularity. We show how both systems serve as a sensitive probe to unravel the stress balance at molecular scale.