Dresden 2011 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 1: Focus Session: Dense Granular Flow

DY 1.5: Hauptvortrag

Montag, 14. März 2011, 12:30–13:00, HÜL 186

Confined granular materials: stability, chute flows and grain motion — •Patrick Richard, Jean-Francois Metayer, Alexandre Valance, and Renaud Delannay — Institut de Physique de Rennes, Universite de Rennes I, UMR CNRS 6251, Campus de Beaulieu, 263 av. General Leclerc, 35042 Rennes cedex, FRANCE

We present experimental and numerical results of 3D confined granular materials. We address the issue of the role of the lateral boundaries on the stability and on the flow of such systems. In particular, we find that the presence of flat frictional lateral walls greatly alters the flow features as soon as the width of the flowing layer is of the order of the spacing between the walls or greater. The properties of such confined flow differ significantly from those of unconfined flows. The kinematic properties as well as the stress analysis are presented in details. The shear rate is constant and independent of inclination over much of the flowing layer. In the direction normal to the free surface, the solid volume fraction increases on a scale equal to half the flowing layer depth. Beneath a critical depth grains exhibit creeping and intermittent cage motion similar to that in glasses, causing gradual weakening of friction at the walls. These results underline the open problem of defining a single rheology for confined granular flows.