Velocity profiles, stresses, and Bagnold scaling of sheared granular system in zero gravity

We report the results of three-dimensional event-driven simulations of sheared granular system in a Couette geometry. The simulations use realistic boundary conditions that may be expected in physical experiments. For a range of boundary properties we report velocity and density profiles, as well as forces on the boundaries. In particular, we find that the results for the velocity profiles throughout the shearing cell depend strongly on the interaction of the system particles with the physical boundaries. Even frictional boundaries can allow for significant slippage of the particles, therefore reducing the shear in the system. Next, we present stress distributions both for controlled volume and for controlled stress configurations. We discuss the dependence of solid volume fraction on shear rate under the constant-pressure condition, and Bagnold scaling in volume-controlled simulations. In addition, we study the influence of oscillatory driving of one of the domain boundaries on the system properties. (c) 2005 American Institute of Physics.