Gravity flow of granular solids through orifices of different shapes in a hopper

Numerical investigation of gravity flow of granular solids in a hopper through orifices of different shapes has been conducted using the discrete element method. The simulations are validated by comparing with the experimental results for rapeseed cases. It is observed that with orifices of the same area the flow rate decreases in the order of circle, square, rectangle and triangle, which is similar to the experimental outcome. A formula for flow rate reflecting the effect of orifice shape is obtained, and compared with the Beverloo’s equation. The reasons behind the influence of orifice shape on flow rate are further studied by considering different internal physical properties of the granular system in the arching zone configurations of the hopper. The velocity field of particles and inter-particle forces have been analysed. It is found that these properties near the orifice area vary for different orifice shape, which can be used to explain the influence of orifice shape on particle flow rate