title: Dynamics of grain avalanches.
abstract: We study the nucleation and the growth of avalanches in a model experimental system consisting of a bidimensional packing of noncohesive grains positioned in a rotating drum. We show that the avalanche mass increases linearly in time, and that the growth rate is governed by the velocities of the two up and down fronts. The upper front is shown to propagate upwards with a velocity which is equal to the averaged velocity of the flowing grains, whereas the velocity of the downslope propagating front is approximately equal to twice the avalanche velocity. We describe simple mechanisms which quantitatively account for the observed dynamical properties.
authors.affiliation: Laboratoire des Milieux Désordonnés et Hétérogènes (CNRS-UMR 7603)-Case 86, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Rajchenbach