Density inversion in rapid granular flows: the supported regime |
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Authors: | N Taberlet P Richard J T Jenkins R Delannay |
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Institution: | (1) Groupe Matière Condensée et Matériaux, UMR CNRS 6626, Université de Rennes 1, 35000 Rennes, France;(2) Theoretical and Applied Mathematics, Cornell University, 210, Kimball Hall Ithaca, NY 14853, USA |
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Abstract: | This paper presents numerical findings on rapid 2D and 3D granular flows on a bumpy base. In the supported regime studied
here, a strongly sheared, dilute and agitated layer spontaneously appears at the base of the flow and supports a compact packing
of grains moving as a
whole. In this regime, the flow behaves like a sliding block on the bumpy base. In particular, for flows on a horizontal base,
the average velocity decreases linearly in time and the average kinetic energy decreases linearly with the travelled distance,
those features being characteristic of solid-like friction. This allows us to define and measure an effective friction coefficient,
which is independent of the mass and velocity of the flow. This coefficient only loosely depends on the value of the micromechanical
friction coefficient whereas the infuence of the bumpiness of the base is strong. We give evidence that this dilute and agitated
layer does not result in significantly less friction. Finally, we show that a steady regime of supported flows can exist on
inclines whose angle is carefully chosen. |
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Keywords: | 45 70 -n Granular systems 83 80 Fg Granular solids |
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