(412d) A Continuum Theory for Particle Size and Density Segregation

Particulate materials composed of particles with different sizes, material densities, or other material properties tend to segregate during various industrial processes such as filling, transporting and discharging, which has significant consequences on product quality and process efficiency. While particle size difference is the most dominating factor that drives segregation, other effects such as the material density difference can induce segregation that enhances or reduces the segregation due to the particle size difference and thus also plays an important role in determining the final particle distributions.  In this talk, we present a theoretical continuum model for segregation due to both particle size and material density differences based on a recently developed continuum model for bidisperse size segregation by incorporating the “buoyancy” mechanism for density segregation. In this model, a length scale for density segregation is considered, which along with the length scale for size segregation can determine the competition between density segregation and size segregation. Our model is applied to several granular model flows to predict steady state local particle distributions and is compared with discrete element simulations, showing a good agreement.