(265e) The Effect of Particle Shape on Granular Stress

Virtually all solid handling operations involve particles that are non-spherical in shape. However, most fundamental studies of granular material undertaken to date have involved spherical particles. There is a current significant disconnect between the model particles which are used in fundamental research studies and the characteristics of real particles dealt with in industry. While industrial practitioners comprehend fully that the influence of particle shape on particle flow behavior is significant, the role of particle shape in flowing granular systems is not understood.

Hence, a systematic investigation of particle shape on granular flow in a simple configuration - planar shear flow - is conducted. Two classes of two-dimensional non-spherical particles (clusters and chains of varying aspect ratios), all with the same equivalent enclosed area, are simulated with a hard-sphere collision model induced by Lees-Edwards periodic boundaries. The granular stress for these various particle shapes is then determined as a function of the solids volume fraction. For elongated particles, the kinetic stress decreases and the collisional stress increases above that of a single disk as the aspect ratio increases. In addition, the kinetic stress increases and approaches a single disk as the number of clustered particles, used to form a rough particle, increases. The collisional stress for the rough particles initially increases beyond that of a single disk as the number of clustered particles increases and then decreases, approaching a single disk.