Numerical simulation for blockage of cohesive particles in a hopper using the distinct element method and its correlation with experimental results of real cohesive granular materials

Abstract

We numerically simulated the blockage phenomena in the three-dimensional rectangular hopper using the distinct element method (DEM) in which the effects of cohesion forces between particles were taken into account. We also measured the critical blockage states using four different cohesive granular materials, i.e. talc, calcium carbonate, flyash and corn starch. The calculated results describe well the blockage, which is greatly affected by the cohesion force. The mass discharge rate decreases and its relative fluctuation increases with an increase of the cohesion force. The normal and shear stresses on the wall increase with an increase of the cohesion force. We found the critical blockage states by calculation and experiment under the various conditions, and calculated the blockage state diagram using the dimensionless numbers based on the properties which affect the blockage phenomena. The calculated and experimental critical blockage states are described by the same straight line (the critical blockage state line). The results of this study make it possible to predict the critical conditions under which the blockage occurs.