Granular flow simulation in a centrifugal acceleration field

Abstract

The use of the geotechnical centrifuge to obtain scaled physical models is a useful tool in geomechanics. When dealing with granular flows, however, the traditional scaling principles are challenged by the complex rheology of the material and by the non-trivial effects of the Coriolis apparent acceleration. In a laboratory centrifuge, obtaining a clear understanding of these effects is further complicated by the technical difficulties in obtaining flows in steady conditions. In this work, the scaling principles for granular flows are studied using a numerical model based on the discrete-element method. In this way it is possible to obtain a steady flow in a rotating reference frame, and to explore the variation of macroscopic properties by changing the scaling factor and the distance from the rotation centre. The outcome is compared with the prediction obtained with a continuum theory for frictional flows. Results show that granular flows scale consistently only when the Coriolis acceleration is negligible, and are severely altered otherwise. The augmented acceleration field is also responsible for an alteration of the flow state, driving the system towards the inertia-driven collisional regime.