Influence of non-spherical shape approximation on DEM simulation accuracy by multi-sphere method

Hoppers are widely used in many engineering and industrial processes. The discharge of hoppers is one of the most important issues in the industry, and our main focus in this project is the discharge behavior in the hoppers. Many factors affect the flow rate and discharge time in the hoppers including particle shape, material properties and hopper type. In this study, discharge of non-spherical particles from the flat bottom hoppers has been simulated using a discrete element method (DEM), which is a technique for granular systems. In order to model the elliptical particles in the experiment, multi-sphere method was used, which is a suitable method for approximation of curved and smooth surface particles. Model was validated using experimental results in the literature and good agreement between them in particle static packing, the flow behavior and hopper discharging rates was found. An important factor that influences the accuracy of the simulation of non-spherical granular systems is the accuracy in modeling of the partides. For this purpose, non-spherical granular particles were modeled with several arrangements of spheres, and the effect of three parameters including the number of spheres forming particles, shape factor, and angularity factor (which indicates the accuracy of the particle shape approximation), on the simulation accuracy was studied. The results briefly showed that the angularity factor, which is a factor affecting the particle surface properties, is an effective parameter controlling the simulation accuracy, such that the linear relationship (R-2 of 0.96 and 0.91) exists between the angularity factor and simulation accuracy. (C) 2018 Elsevier B.V. All rights reserved.