Effect of particle shape on the packing fraction and velocity profiles at the outlet of a silo

Abstract

Abstract Many studies on how the particle shape affects the discharge flow mainly focus on discharge rates and avalanche statistics. In this study, the effect of the particle shape on the packing fractions and velocities of particles in the silo discharge flow was investigated by using discrete element method. The time-averaged packing fraction and velocity profiles through the aperture were systematically measured for superelliptical particles with different blockiness. Increasing the particle blockiness is found to increase resistance to flow and reduces the flow rate. At an identical outlet size, larger particle blockiness leads to lower velocities and packing fractions at the outlet. The packing fraction profiles display evident self-similar features that can be appropriately adjusted by fractional power laws. The velocity profiles for particles with different shapes obey a uniform self-similar law that is in accord with previous experimental results, which is compatible with the free fall arch hypothesis. To further investigate the origin of flow behaviors, the packing fraction and velocity fields in the region above the orifice were computed. Based on these observations, the flow rate of superelliptical particles was calculated and agrees with the simulated data.