Pure Shear of 2d Granular Mixtures: Simulation

We report on a two-dimensional simulations of mixtures of disks, circulo-rectangles and other irregular shaped particles under pure shear. The system exhibits canonical granular stick-slip motion and, under certain conditions, a transition to solid-body motion. We examine the effect of varying confining pressure and pile height on the velocity profiles and shear stresses, and compare closely with a matched experiment. Higher confining pressures result in increased frequency of bulk motion, with a critical pressure related to the bottom-row friction required to induce motion at the bottom. To compare with experiment, we examine both smooth and rough container boundaries. We quantitatively compare velocity field and shear stress, as well as height and composition dependence of shear stress and pile bulk-motion. Finally, we are able to use experimental images to set the initial pile configuration and compare individual particle locations to determine fidelity of simulation to experiment.