Bidisperse Granular Flow on Inclined Rough Planes

Summary

Experiments on bidisperse dry granular flows on an inclined rough plane were made in order to better understand the rheology of this kind of material. Flows, created by a localised input of a granular matter onto the plane, propagate and spread laterally, being unconfined by the experimental set-up. Because of size segregation, the lateral and vertical inhomogeneous repartitions of particles lead to several effects causing the main difference between bidisperse and monodisperse flow: the outline effect and the interfaces effects. The outline effect is due to the large beads at the front, and at the borders of the flow. It can be interpreted using the relative frictions of the two types of beads on the rough plane. The relative friction has been quantified with experiments on monodisperse granular flows. The interfaces effects deal with the interaction between the layers of large and small beads and with the interaction between the small beads and the plane. It combines friction, dragging and longitudinal separation of th etwo superposed layers of beads.