title: Collapse dynamics and runout of dense granular materials in a fluid.
abstract: We investigate the effect of an ambient fluid on the dynamics of collapse and spread of a granular column simulated by means of the contact dynamics method interfaced with computational fluid dynamics. The runout distance is found to increase as a power law with the aspect ratio of the column, and, surprisingly, for a given aspect ratio and packing fraction, it may be similar in the grain-inertial and fluid-inertial regimes but with considerably longer duration in the latter case. We show that the effect of fluid in viscous and fluid-inertial regimes is to both reduce the kinetic energy during collapse and enhance the flow by lubrication during spread. Hence, the runout distance in a fluid may be below or equal to that in the absence of fluid due to compensation between those effects.
authors.affiliation: Institut de Radioprotection et Sûreté Nucléaire, PSN, CE Cadarache, BP3-13115 St Paul-Lez-Durance Cedex, France.
authors.forename: V
authors.initials: V
authors.lastname: Topin
authors.forename: Y
authors.initials: Y
authors.lastname: Monerie
authors.forename: F
authors.initials: F
authors.lastname: Perales
authors.forename: F
authors.initials: F
authors.lastname: Radjaï