Strength Deterioration of Nonfractal Particle Aggregates in Simple Shear Flow

The restructuring of a nonfractal particle aggregate in simple shear flow was simulated by a Stokesian dynamics approach. We studied the deformation and the resultant strength change of aggregates by the surrounding flow under the condition that the cohesive strength of an aggregate is comparable to the fluid stress. In particular, we focused on how the aggregate deteriorates because of the fluid stress exerted on it periodically. The image analysis was applied to visualized simulation results for the quantitative estimation of irreversible change in an aggregate configuration. We examined the structural change in the aggregate from various perspectives, i.e., the outer shape, the internal strength, and the fluid stress on the surface of the aggregate. The simulation results show that the aggregate gets squashed after an intricate restructuring process and it elongates along with the streamline as experimentally observed in the previous study. Regarding the internal strength, the weakest point locally develops in the aggregate by periodically varying the fluid stress. A combination of rotation and elongation effects of shear flow is complexly involved in the deterioration of the internal strength of the aggregate.