Hopper Flows of Mixtures of Spherical and Rod-Like Particles via the Multisphere Method

The discharge of granular media from hoppers plays a vital role in many solids handling operations. The dynamic flow of poly-disperse nonspherical particles differs markedly from mono-disperse spheres and highlights the need to rigorously account for particle shape effects. The multisphere discrete element method (MS-DEM) was utilized here to examine the bulk packing fraction, discharge rate, collisional stress tensor, and order parameter of a bi-disperse sphere-rod mixture evacuating a hopper. A modified form of the Myers and Sellers correlation with variable shape factor is capable of replicating the MS-DEM discharge data. The collisional stress tensor is observed to be highly symmetric for mono-disperse spheres but becomes asymmetric when rod-like particles are introduced. The order parameter within the hopper increases significantly during discharge and the rod-like particles undergo shear induced alignment with their long dimensions orthogonal to the outflow plane.