Simulations of Granular Flow in Silos with Different Finite Element Programs: ANSYS vs. SILO

Great effort has been made to improve the knowledge about the behavior of granular material in silos. Nevertheless, many important aspects such as wall pressure, to which silo structures are subjected, still remain uncertain. Numerical simulations based on the finite element method have become a valuable tool to simulate the behavior of granular material in silos at rest and during their flow and to estimate the actions for which the structure has to be designed. However, great differences between various FE software packages have been observed. In this article, the results of two different FE software packages, the general-purpose software ANSYS and a special non-linear dynamic program called SILO, are compared, and the main problems of numerical simulations of granular flow in silos are discussed. Stresses of granular material are calculated during filling and discharge for two- and three-dimensional geometries, including different eccentricities of the outlet. Some numerical problems appear in both models when the bin is filled in several layers. Lateral pressures obtained with both models are similar for filling, but several differences may be observed during discharge. The ANSYS model presents some problems after short simulation discharge time, while the SILO model can simulate almost the entire process of discharge.