Coating of a textured solid

Jacopo Seiwert (1, 2) , Christophe Clanet (1, 2) , David Quéré (1, 2)

1 LadHyX - Laboratoire d'hydrodynamique
2 PMMH - Physique et mécanique des milieux hétérogenes (UMR 7636)

We discuss how a solid textured with well-defined micropillars entrains a film when extracted out of a bath of wetting liquid. At low withdrawal velocity V, it is shown experimentally that the film exactly fills the gap between the pillars; its thickness hd is independent of V and corresponds to the pillar height hp. At larger velocity, hd slowly increases with V and tends towards the Landau-Levich-Derjaguin (LLD) thickness h LLD observed on a flat solid. We model the entrainment by adapting the LLD theory to a double layer consisting of liquid trapped inside the texture and covered by a free film. This model allows us to understand quantitatively our different observations and to predict the transition between hp and hLLD. © 2011 Cambridge University Press.

Domains: Physics [physics]; Mechanics [physics]; Fluid mechanics [physics.class-ph]; Engineering Sciences [physics]; Mechanics [physics.med-ph]; Fluids mechanics [physics.class-ph]

Jacopo Seiwert, Christophe Clanet, David Quéré. Coating of a textured solid. Journal of Fluid Mechanics, 2011, 669 (february), pp.55-63. ⟨10.1017/s0022112010005951⟩. ⟨hal-00997969⟩