The Influence of the Particle Shape on the Discharge Rate from the Model Silo

  • Kobyłka, Rafał (Institute of Agrophysics, PAS)
  • Horabik, Józef (Institute of Agrophysics, PAS)
  • Govender, Nicolin (University of Johanesburg; RCPE)
  • Khinast, Johannes (Technical University of Graz; RCPE)

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Although real particle systems are composed of irregular particles, the majority of reported research papers has based DEM simulations on spheres due to their simplicity and relatively low computational cost, leaving the behaviour of non-spherical particles unexplored in many areas. One of such gap is the influence of the shape factor on the behaviour of the particles during silo discharge. The Beverloo equation (eq. 1) is the most widely accepted empirical model for predicting mass discharge rate (MDR): MDR=C ρ g^(1/2) ( L−k d p )^(5/2), (1) where, ρ is the bulk density of the material, g is the acceleration of gravity, L is the size of the orifice, d p is the diameter of the particles, and C and k are the fitting parameters. The variation of C and k with non-spherical particles based on polyhedra has been studied in this project. The regular icosahedron (20 faces), octahedron (8 faces), hexahedron (6 faces) and tetrahedron (4 faces) were tested and their behaviour was compared with spherical particles in order to evaluate the dependence of the roundness on the MDR and the internal force chain distribution. The GPU-Based DEM software Blaze-DEM, developed by Govender et. al. [1] and modified to include polyhedral shapes, was used. Based on our analysis the following conclusions were drawn: - The spherical particles, even with an artificial rolling friction cannot reproduce the behaviour of polyhedral particles. - A transition from friction-based contacts, for most round shapes (sphere, isosahedron), to interlocking (tetrahedron, hexahedron) was observed. REFERENCES [1] N. Govender, D.N. Wilke, S. Kok, Blaze-DEMGPU: Modular high performance DEM framework for the GPU architecture, SoftwareX, 5, 62-66 (2016).