Granular flows in a rotating drum: the scaling law
between velocity and thickness of the flow |
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Authors: | G Félix V Falk U D'Ortona |
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Institution: | (1) Laboratoire des Sciences du Génie Chimique, UPR 6811, CNRS, BP451, ENSIC, INPL, 1 rue Grandville, 54000 Nancy, France;(2) Laboratoire de Modélisation et Simulation Numérique en Mécanique et Génie des Procédés, 38 rue Frédéric Joliot-Curie, 13451 Marseille Cedex 20, France |
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Abstract: | The flow of dry granular material in a half-filled rotating drum is studied. The thickness of the flowing zone is measured
for several rotation speeds, drum
sizes and beads sizes (size ratio between drum and beads ranging from 47
to 7400). Varying the rotation speed, a scaling law linking
mean velocity vs. thickness of the flow, v∼hm, is deduced for each couple
(beads, drum). The
obtained exponent m is not always equal to 1, the value previously reported for a drum in litterature, but varies with the
geometry of the system.
For small size ratios, exponents higher
than 1 are obtained due to a saturation of the flowing zone thickness.
The exponent of the power law decreases with the size ratio, leading
to exponents lower than 1 for high size ratios. These exponents imply that
the velocity gradient of a dry granular flow in a rotating drum
is not constant. More fundamentally, these results show that the flow of a
granular material in a rotating drum is very sensible to the geometry, and that
the deduction of the “rheology” of a granular medium flowing in such a
geometry is not obvious. |
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Keywords: | 45 50 -j Dynamics and kinematics of a particle and a system of particles 45 70 -n Granular systems |
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