Effect of shear friction on solid flow through an orifice

Abstract

A model to predict the flow rate of particulate solids through an orifice is developed based on force and momentum balances at the stress-free surface (SFS), which occurs near the orifice. It is shown that shear friction between flowing and nonflowing particles around edges of the bottom orifice in standpipes is an important factor to be taken into account. The model utilizes a simplified description of the effects of shear friction between flowing and stagnant particles. The resulting equation has a similar form to Beverloo's equation but with an added term for avoiding the orifice size correction inherent in the Beverloo form.