Abstract
High-level control of the particle packing structure in a container requires the detailed analysis of particle size segregation during gravity filling. Here, we propose a method for analyzing quantitatively the effect of particle shape on the size segregation of particles using DEM (Distinct Element Method) simulation, which employ spherical particles with an equivalent friction coefficient to efficiently incorporate the effect of particle shape, is proposed.
The simulation of container filling is carried out for particles having a continuous particle size distribution, including different particle shapes. In order to quantitatively evaluate the particle size segregation into the active layer, two metrics are used: a new segregation index indicating the degree of segregation and the percolation index, which evaluates the percolation segregation. Using spherical glass beads, and irregular-shaped Ise sand and alumina particles, the filling behavior of particles into a container are simulated, and the segregation index of those filling layer are estimated. Although increasing the irregularity of particles reduces the mobility of particles, the segregation index of those filling layer conversely become large. Then, the segregation behavior of particles is analyzed using the percolation index. As a result, it is clear that while the coarse particles serve as a frame layer and flow slowly in the center of heap due to the high friction characteristic, the fine particles percolate down; moreover the segregation of coarse particles as a frame layer increase at the bottom of the heap because the velocity gradient of particles under shear flow also increase.
