ABSTRACT
A simple shear flow of granular materials can have a range of behavior from a rate-independent plastic material to a rate-dependent viscous material. It is known that this constitutive relation is a consequence of the shear-rate, the solid concentration, and the micromechanical properties of the particles. In the rate-independent case, a shearing granular assembly forms crystallized regions and shearing occurs locally in a narrow band. In the rate-dependent case, these crystallized zones ‘melt’ and the whole granular assembly participates in the shear motion. This study utilizes computer simulation to address yet another effect on the constitutive relation: the sample size. Through investigating details of the kinematics of the shearing assembly, we examine source of this transition from a rate-independent to a rate-dependent fluid as the sample size increases.
