The Dynamics of Granular Flow in Hopper Silos

ABSTRACT: Particle Image Velocimetry (PIV) based experimental tests have been used to investigate the granular flow properties in a half model smooth-sided silo hopper. This paper shows that the flow patterns and dynamic flow properties of a model silo system under natural gravity can be effectively captured using PIV. The technique appears to be a valuable additional tool for practical and experimental capture of the material flow. The results in the paper show that the flow mechanisms in a silo are quite complex and vary temporally and spatially. Three distinct zones of behaviour were observed: a) an upper inflow zone, b) a narrow vertical funnel flow zone and c) a near static stagnant zone. The characteristics of these flow zones are likely to be influenced by the material and geometric properties of the silo. Additional testing will be conducted by the researchers with other materials, silo geometries and enhanced gravities in the centrifuge, to further understand the physical processes involved and the limitations of the experimental methods.