title: Flow of wet granular materials.
abstract: The transition from frictional to lubricated flows of a dense suspension of non-Brownian particles is studied. The pertinent parameter characterizing this transition is the Leighton number Le=eta(s)gamma / sigma, the ratio of lubrication to frictional forces. Le defines a critical shear rate below which no steady flow without localization exists. In the frictional regime the shear flow is localized. The lubricated regime is not simply viscous: the ratio of shear to normal stresses remains constant and the velocity profile has a universal form in both frictional and lubricated regimes. Finally, a discrepancy between local and global measurements of viscosity is identified, which suggests inhomogeneity of the material under flow.
authors.affiliation: Laboratoire de Physique Statistique, UMR 8550 CNRS, Ecole Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France.
authors.forename: N
authors.initials: N
authors.lastname: Huang
authors.forename: G
authors.initials: G
authors.lastname: Ovarlez
authors.forename: F
authors.initials: F
authors.lastname: Bertrand
authors.forename: S
authors.initials: S
authors.lastname: Rodts
authors.forename: P
authors.initials: P
authors.lastname: Coussot
authors.forename: Daniel
authors.initials: D
authors.lastname: Bonn