Wicking in a Powder

P. S. Raux (1, 2) , H. Cockenpot (1, 2) , M. Ramaioli (3) , David Quéré (1, 2) , Christophe Clanet (1, 2)

1 LadHyX - Laboratoire d'hydrodynamique
2 PMMH - Physique et mécanique des milieux hétérogenes (UMR 7636)
3 Department Food Science & Technology

We investigate the wicking in granular media by considering layers of grains at the surface of a liquid and discuss the critical contact angle below which spontaneous impregnation takes place. This angle is found to be on the order of 55 for monodisperse layers, significantly smaller than 90, the threshold value for penetrating assemblies of tubes. Owing to geometry, impregnating grains is more demanding than impregnating tubes. We also consider the additional effects of polydispersity and pressure on this wetting transition and discuss the corresponding shift observed for the critical contact angle.

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

P. S. Raux, H. Cockenpot, M. Ramaioli, David Quéré, Christophe Clanet. Wicking in a Powder. Langmuir, 2013, 29 (11), pp.3636-3644. ⟨10.1021/la400015v⟩. ⟨hal-00994467⟩