A Numerical Model for Flow of Granular Materials in Silos. Part 3: Parametric Study

Abstract

Abstract A hybrid numerical model for the solution of bulk solids flow in silos and bins was used for the analysis of flow in symmetric and asymmetric rectangular bins. Seven analyses in symmetric bins with varying wall frictions, hopper slopes and discharge openings were carried out. In the four asymmetric bin analyses only the wall friction was varied. Friction between stored material and bin wall was the most important factor affecting wall pressures throughout the bin. The maximum wall pressure at the junction of the parallel bin and hopper increased from 38 kPa for a friction coefficient of 0·5 to 63 kPa for a coefficient of 0·2. The overpressures that occurred at the flow constriction caused by a hopper with a 0·4 m discharge opening were 6–7% smaller than those in which the opening was 0·8 m wide. The discharge velocity was 6·3% greater at the larger width. An increase in the hopper angle from 28 to 50° caused a decrease in discharge velocity of about 5·5%, but an increase in normal wall pressure at the junction of the parallel bin and hopper of about 15%. In the asymmetric hopper, mirror image of overpressures occurred along the straight wall at the level where the hopper caused a flow constriction, but these overpressures were lower than those at the discontinuity itself. The ratio of the maximum pressures ranged from 1·6 for a friction coefficient of 0·2 to 2·1 for a coefficient of 0·5.