Boundary conditions for rapid granular flows: phase interfaces

Publisher Website
Google Scholar
Abstract
We consider the region of agitated grains that is at rest in the neighbourhood of its interface with a dense granular flow. We suppose that this region can be modelled as an amorphous solid of nearly elastic spheres in which both momentum and energy are transferred and energy is dissipated in collisions. Making rather rough assumptions about the collision probability, we calculate the stress and energy flux in the solid and use their continuity at the interface to obtain boundary conditions on the flow. We employ them with existing kinetic theory for nearly elastic spheres to solve boundary-value problems for shearing between two such interfaces and between such an interface and a flat plate to which spheres have been rigidly attached. For the latter, we compare the predictions of the theory with the results of experiments.