(368d) Transport Analogies for Segregation in Granular Shear Flows

Shear induced segregation is a problem of considerable import both industrially and academically. As a granular material is sheared, the bed dilates and heavier (or smaller) particles move perpendicular to the mean flow. In the present work, we perform a computational study -- based on the Discrete Element Method -- of the flow in a simple boundary-driven planar shear cell. Inside the cell is a mono-disperse light particle packing that includes several heavier intruder particles which are used to measure density segregation for a variety of flow conditions: differing density ratios, shear rates, confining pressures (for constant pressure boundary conditions) or solids' fractions (for constant volume boundary conditions). We find that the underlying granular rheology has a profound effect on the rate of the segregation process. In particular, we note that by choosing the proper scaling we can identify a transition in segregation rate between a "quasi-static" and "intermediate" regime. These results suggest that one can construct an analogy between segregation and granular flow that is akin to transport analogies (like the Colburn or Reynolds analogy) in continuum fluids processing.