Formulation of stresses in dry granular flows

Abstract

We employ in this paper a Discrete Element Modelling (DEM) method to characterize rheology of dry, dense granular flows. We particularly look at the formulation of macroscopic system stresses based on the forces acting on individual particles. In addition, we study the possible coexistence in a domain of interest of different regimes of granular flow. The modelling framework is implemented in an open-source computational framework (OpenFOAM) in order to simulate dry granular flow in a Couette shear cell. The system is dense with particle volume fractions close to the maximum packing of particles. To accurately describe the contact forces on the particles, a soft-sphere model is used. Our simulations identify the following trends in the behaviour of granular material: increasing the values of the solid volume fraction, shear rate or friction, respectively, unambiguously leads to both higher stresses and their different distribution in the system. Finally, tendencies on the ratio between shear and normal stresses are investigated as a function of the volume fraction