FE-studies on rapid flow of bulk solids in silos

Abstract

This paper contains results of numerical modelling of the onset of silo flow for granular material in a model silo with convergent walls. The calculations were performed with a finite element method based on a polar elasto-plastic constitutive relation by Mühlhaus. It differs from the conventional theory of plasticity by the presence of Cosserat rotations and couple stresses using a mean grain diameter as a characteristic length. The characteristic length causes that numerical results do not depend upon the mesh discretisation. The model tests on rapid silo flow of glass beads performed by Renner in a glass hopper with a large wall inclination from the bottom were numerically simulated. The FE-calculations were performed for plane strain by taking into account inertial forces and linear viscous damping. A satisfactory agreement between numerical and experimental results was obtained. In addition, the FE-calculations were performed for very rough walls. Advantages and limitations of a continuum approach for simulations of rapid silo flow were outlined.

Finite element investigation of the flow and stress patterns in conical hopper during discharge

“…2. As observed by Tejchman and Klisiński (2001) and other researchers, Lagrangian FEM leads to increasing distortions of the computational mesh with the continuous outflow of material in the vicinity of outlet, which is a distinct contrast to the present Eulerian FEM.…”

“…To make a comparison, the same exercise is also carried out with the ordinary Lagrangian FEM (Abaqus 6.10/Explicit), details of which can be found elsewhere (Tejchman and Klisiński, 2001;Goodey et al, 2003Goodey et al, , 2006Yang et al, 2011). The difference between the two methods in simulation of discharge can be clearly seen from Fig.…”

“…FEM associated with elastoplastic constitutive theories can give satisfactory predictions of the internal stress and wall pressure in hoppers (Ooi and Rotter, 1990;Rotter et al, 1998;Goodey et al, 2003Goodey et al, , 2006Goodey and Brown, 2004;Vidal et al, 2006Vidal et al, , 2008Ding et al, 2013). However, its application to reproduce the flow conditions of granular material is usually not easy Sanad et al, 2001;Tejchman and Klisiński, 2001) and requires some particular schemes or treatments such as the re-meshing and re-zoning scheme (Sanad et al, 2001), adaptive meshing technique (Yang et al, 2011), viscoplastic granular fluid models (Haussler and Eibl, 1984;Karlsson et al, 1998;Elaskar et al, 2000;Böhrnsen et al, 2004), smoothed particle hydrodynamics (SPH) method (Sugino and Yuu, 2002), and material point method (MPM) (Wieckowski et al, 1999).…”