Flow and wall stress analysis of granular materials around blocks attached to a wall

Abstract

Granular flow around boundary walls at geometric discontinuities can create extreme forces and momenta that deviate significantly from those in a controlled and well understood setting of unobstructed flow. Therefore, the study of the flow dynamics of granular materials in the near wall region is necessary to better understand the causes and implications of the resulting forces of the flow, so as to help protect industrial equipment. This paper presents a numerical study of solid flow around blocks attached to a wall under simplified conditions by means of the discrete element method. Flow patterns, particle velocities, and particle-particle/particle-wall interaction forces are analysed at the macro and particle scale. The results demonstrate different flow regions and flow characteristics including stagnant zones between blocks where particle velocities are minuscule, uniformly moving plug flow zone in undisturbed areas, and particle-free zones below blocks. The presence of blocks reduces the effect of the overlying burden on the stress transfer within the granular assembly, but leads to high forces in the areas above blocks. Force peaks acting on the side walls follow the block location, with the maximum force occurring at the intersection of the upper block face and vertical wall. The influence of block spacing predominantly manifests itself in areas close to the blocks with an ideal spacing of 7–15 particle diameters required to attain minimum particle-wall forces on the vertical wall elements. The findings are useful in better understand the relationship between structural elements of bulk material handling equipment and their effect on granular flow dynamics.