Experimental and DEM studies of velocity profiles and residence time distribution of non-spherical particles in silos

Abstract

Residence time distribution (RTD) of barley grains with elliptical shape were investigated in wedge-shaped and flat-bottom silos using the discrete element method (DEM) and experiments. The velocity distribution of particles were captured using particle image velocimetry during silo discharge. Multi-sphere method (a combination of three spheres) was used to simulate the granular flow by DEM. The model was validated using the experimental results relative to distributions of lateral and axial components of particle velocity. The obtained RTDs were interpreted using the flow pattern of particles. In the flat-bottom silo, the regions on the top of the outlet showed the shortest residence times. The residence times of particles increased as the height increased above the outlet, in the center of the silos. In the regions close to the walls (outside of the outlet region) of the flat-bottom silo, residence time of particles decreased with increasing height. On the other hand, in the wedge-shaped silo, particles in the outlet zone showed the shortest residence times while the particles located on the inclined silo wall out of the outlet zone have the longest residence times. Effects of wedge angle and initial filled height were also studied and discussed on the residence time distribution.