Slow flows of granular materials, which typically occur during emptying of industrial storage hoppers and bins, have great industrial relevance. In this paper, we use the Dilatant Double Shearing model to study the slow flow of a dense granular material. The Dilatant Double Shearing constitutive equations are accompanied by the continuity and momentum equations to yield a complete set of equations describing the flow of dense and frictional granular materials. Unlike some recent models (Tardos, etc., 1997, 2003) that pertain only to fully developed flows, the application of this approach is shown to be valid from the onset of discharge to fully developed flow. In our study, we use the Finite Element program ABAQUS EXPLCIT to numerically simulate the Couette flow and the flow in a silo. We compare our results with DEM results for Couette flow by Karion and Hunt. The relative density variation and the velocity profile obtained using double shearing model are in good agreement with those obtained from DEM. For the simulation of slow frictional flow in a silo, the major principal stress directions are obtained at various time steps after the onset of silo discharge. We also compare the pressure distribution along the wall before and after the onset of silo discharge and obtained the velocity profile and relative density distribution during discharge. In conclusion, we show that the Dilatant Double Shearing constitutive model can be used to simulate the slow, frictional granular flow.
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