Computations of granular flow and pressures in a flat-bottomed silo

The most demanding design situations for silo structures usually occur at the onset of discharge, when the silo is still almost full of granular solid. In this condition, the pattern of solids flow affects the wall pressures, and both are currently difficult to predict even using the best numerical models. This paper describes part of an international collaborative study in which finite element and discrete element models were used by many leading research groups around the world to model a single well-defined problem of discharge from a flat-bottomed silo using many different programs. The results show that discrete element models give good qualitative predictions of flow patterns, and the finite-element models give good quantitative predictions of pressure regimes, but there is little agreement on the details either within each modeling paradigm or between them. Further extensive research is needed to reach a scientific consensus on the requirements for a reliable formulation.