ABSTRACT
Granular material poured on a static heap of the same material generates a flow which is localized in a relatively thin layer (10-20 particle diameters) at the surface. As particles flow they may erode the heap or deposit on it, and interchange of particles between the layer and the heap is a characteristic of such surface flows. The local angle of the heap surface, the depth of the flowing layer and the mean velocity of the particles is determined by the flow. For example, externally increasing the surface angle of a heap could lead to a higher mean particle velocity and also a thicker flowing layer resulting from additional layers of particles in the heap set in motion. Clearly, the “boundary” between the flowing layer and the heap is unknown a priori and is determined by the flow itself. This is a unique feature of this type of granular flow.
