Europhys. Lett., 63 (1) , pp. 42-48 (2003)
Diphasic non-local model for granular surface flowsD. Bonamy1, 2 and P. Mills3
1 Service de Physique de l'Etat Condensé, CEA Saclay 91191 Gif-sur-Yvette Cedex, France
2 Laboratoire des Verres, Université Montpellier 2 F-34095 Montpellier Cedex 5, France
3 Laboratoire de Physique des Matériaux Divisés et des Interfaces Université Marne la Vallée - 77454 Marne la Vallée Cedex 2, France
(Received 5 June 2002; accepted in final form 30 April 2003)
Considering recent results revealing the existence of multi-scale rigid clusters of grains embedded in granular surface flows, i.e. flows down an erodible bed, we describe here the surface flows rheology through a non-local constitutive law. The predictions of the resulting model are compared quantitatively to experimental results: The model succeeds in accounting for the counter-intuitive shape of the velocity profile observed in experiments, i.e. a velocity profile decreasing exponentially with depth in the quasi-static phase and remaining linear in the flowing layer with a velocity gradient independent of both the flowing layer thickness, the angle between the flow and the horizontal, and the coefficient of restitution of the grains. Moreover, the scalings observed in rotating drums are recovered, at least for small rotating speed.
45.70.-n - Granular systems.
83.80.Fg - Granular solids.
45.05.+x - General theory of classical mechanics of discrete systems.
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