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O. Barbir, B. Stimac:
"Influence of gravity on granular flow in silo centrifuge models in comparison with Beverloo equation";
Supervisor: W. Wu, J. Mathews; BOKU Wien - Institut für Geotechnik, 2013; final examination: 2013-09.

The flow of granular materials through an orifice has been a subject of numerous studies for decades due to its importance for proper industrial silo design, which can significantly minimize the failure rate. The most widely accepted law that predicts the flow rate of grains through an orifice was proposed by Beverloo et al. (1961).
Le Pennec et al. (1995) observed mass flow rate of several materials with variation of particle sizes through a circular orifice. They concluded that up to 13g there is no measurable influence on the interactions between particles on the mass flow rate of the materials, thereby giving strong confirmation of the Beverloo equation.
We investigate the effect of higher gravity of up to 15g and the influence of the particle size and hopper angle on flow rate using fine and course sand in combination with two silo geometries. The two geometries used are a silo with a 30° hopper and a silo with a flat bottom. The results are compared with the Beverloo equation for a slit orifice of a quasi-two-dimensional silo, as well as with the equation presented by Rose and Tanaka (1956) regarding influence of hopper angle on the flow rate.
Our test results show a strong correlation with Beverloo equation even in higher gravity levels of up to 15g. It is therefore confirmed that the equation still gives good results when gravity is increased.

granular flow, silo design, centrifuge modelling, Beverloo equation