Flow rule, self-channelization and levees in unconfined granular flows

Stéphanie Deboeuf (1, 2) , Eric Lajeunesse (2) , Olivier Dauchot (3) , Bruno Andreotti (4, 5, 6)

1 DALEMBERT - Institut Jean Le Rond d'Alembert
2 IPGP - Institut de Physique du Globe de Paris
3 SPEC - UMR3680 - Service de physique de l'état condensé
4 MSC - Matière et Systèmes Complexes
5 LPS - Laboratoire de Physique Statistique de l'ENS
6 PMMH - Physique et mécanique des milieux hétérogenes (UMR 7636)

Unconfined granular flows along an inclined plane are investigated experimentally. During a long transient, the flow gets confined by quasistatic banks but still spreads laterally towards a well-defined asymptotic state following a nontrivial process. Far enough from the banks a scaling for the depth averaged velocity is obtained, which extends the one obtained for homogeneous steady flows. Close to jamming it exhibits a crossover towards a nonlocal rheology. We show that the levees, commonly observed along the sides of the deposit upon interruption of the flow, disappear for long flow durations. We demonstrate that the morphology of the deposit builds up during the flow, in the form of an underlying static layer, which can be deduced from surface velocity profiles, by imposing the same flow rule everywhere in the flow.

Domaines: Matière Molle [cond-mat.soft]

Stéphanie Deboeuf, Eric Lajeunesse, Olivier Dauchot, Bruno Andreotti. Flow rule, self-channelization and levees in unconfined granular flows. Physical Review Letters, 2006, 97 (15), pp.158303. ⟨10.1103/PhysRevLett.97.158303⟩. ⟨hal-00200717⟩