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O. Barbir, J. Mathews:
"Investigation of the influence of gravity on granular flow using silo centrifuge model";
Vortrag: 25th European Young Geotechnical Engineers Conference, Sibiu, Romania (eingeladen); 21.06.2016 - 24.06.2016; in: "Proceedings of the 25th European Young Geotechnical Engineers Conference", (2016).

The flow of granular material through an orifice has been a subject of numerous studies for decades due to its importance for proper industrial silo design. The most widely accepted law that predicts the flow rate of grains trough an orifice was proposed by Beverloo et al. (1961).
The velocity field within the silo during discharge cannot be reliably predicted yet, and the mechanisms controlling discharge from silos remain unclear. In this work an investigation into gravity discharge from silos in increased gravity conditions is presented. Increased gravity conditions were modelled in the geotechnical centrifuge, where the gravity was increased up to the factor of 15. Materials differing in particle sizes were tested using two different silo model geometries. The results were then compared to 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.
It was shown that the mass flow rate as well as the local velocity of discharging is proportional to the square root of gravity and that the time required for a silo model to discharge cohesionless material scales with gravity. Analysis of the time required to discharge a silo leads to the observation of a scaling law for silo centrifuge models.

granular flow, silo design, centrifuge modelling, Beverloo equation

http://publik.tuwien.ac.at/files/PubDat_249990.pdf