(348d) Predicting Granular Density Segregation—a Kinetic Theory Approach

In dense granular flows, particles of different densities segregate as they flow. Here we use momentum conservation equations for individual constituents to derive an expression for the segregation velocities of density bidisperse segregating species in a dense granular flow. These segregation velocities are then used in a proposed relation based on the kinetic theory of granular flow that was originally derived for dilute granular flows. The relation for dilute flows is modified to include terms to account for the effects of the local inertial number, the relative species concentrations, the particle surface friction, and the coefficient of restitution that are typical of dense granular flows. The segregation velocities derived from this approach agree well with DEM simulations in both uniform and nonuniform shear flows of density bidisperse particles, accurately predicting the difference between upward species velocity and downward species velocity for different density ratios and relative constituent concentrations. The ongoing challenge is to extend this model to size bidisperse particles, a much more difficult problem.