Granular Segregation in Collisional Shearing Flows

This paper considers segregation in collisional granular shearing ows from the experimental, computational, and theoretical standpoints. We focus on a phenomenon of segregation where the separation of grains by size or mass is driven by spatial gradients in the uctuation energy of the grains. We report experiments carried out in microgravity with a shear cell shaped as a race track and containing a mixture of two types of spherical grains. In those experiments, a gradient of uctuation energy was produced between an inner moving boundary driving collisions among the grains and an outer, more dissipative boundary at the periphery of the cell. The grain segregation and the velocity statistics were captured by a rapid video camera and analyzed using computer-vision software. We brie y outline a kinetic theory and simulations for these ows. We compare the corresponding pro les of granular concentration, mean velocity, and uctuation energy with the experimental results.