Effect of system size on particle-phase stress and microstructure formation

In this paper, we investigate the effect of particle number, or system size, on three-dimensional (3D) particle dynamic simulation results. Specifically, we simulate conditions with varying e (coefficient of restitution) and phi (solids volume fraction), containing particle numbers ranging from 250 to 300 000. Various algorithmic improvements are implemented in the simulation to efficiently handle these large numbers of particles. We observe, for the first time for 3D simulations, particle-phase microstructure formation at high coefficients of restitution. Furthermore, we show the onset of the particle-phase microstructure formation at various threshold system sizes, depending on the value of e and phi, and relate it to an increase in particle-phase stress. Visual observations are used to conduct a preliminary investigation of the nature of the microstructure formation. Multiple well-defined bands are observed for simulations of at least 100 000 particles. (C) 2004 American Institute of Physics.