title: Air entrainment by contact lines of a solid plate plunged into a viscous fluid.
abstract: The entrainment of air by advancing contact lines is studied by plunging a solid plate into a very viscous liquid. Above a threshold velocity, we observe the formation of an extended air film, typically 10 microns thick, which subsequently decays into air bubbles. Exploring a large range of viscous liquids, we find an unexpectedly weak dependence of entrainment speed on liquid viscosity, pointing towards a crucial role of the flow inside the air film. This induces a striking asymmetry between wetting and dewetting: while the breakup of the air film strongly resembles the dewetting of a liquid film, the wetting speeds are larger by orders of magnitude.
authors.affiliation: Physique et Mécanique des Milieux Hétérogènes, UMR 7636 ESPCI -CNRS, Université Paris-Diderot, 10 rue Vauquelin, 75005, Paris.
authors.forename: Antonin
authors.initials: A
authors.lastname: Marchand
authors.forename: Tak Shing
authors.initials: TS
authors.lastname: Chan
authors.forename: Jacco H
authors.initials: JH
authors.lastname: Snoeijer
authors.forename: Bruno
authors.initials: B
authors.lastname: Andreotti