(432f) A Segregation Force Model for Mixtures

Segregation of bidisperse particle mixtures is characterized by species concentration and particle size and density ratios. As the concentration of one species approaches zero, corresponding to the single particle limit, the problem reduces to that of an intruder in a homogenous bed, for which previous studies have successfully modeled the segregation driving force as a function of size and density ratios. This model consists of two multiplicative terms that account for percolation and buoyancy, respectively. However, a general segregation force model is still lacking for mixtures having non-zero species concentrations. Here we extend the virtual-spring-based force measurement approach used for single intruders in DEM simulations to bidisperse mixtures for a wide range of particle species concentrations, properties, and flow conditions. Based on the simulation data, we propose a segregation force model that depends on species concentration, thus bridging the gap between single intruder motion and mixture segregation. Our results show that the segregation force varies smoothly with concentration. For large-particle concentrations less than 0.5, the scaled segregation force is nearly equal to that for a single intruder. Funded by NSF Grant CBET-1929265.