Restructuring Capability of Non-Fractal Aggregate in Simple Shear Flow

Abstract

We have performed numerical simulation to investigate the restructuring capability of an isolated non-fractal aggregate in simple shear flow. The change in structure of aggregate having different initial packing properties is numerically examined by a Lagrangian approach. Stokesian dynamics is employed as a rigorous method for the calculation of the hydrodynamic interaction, while the inter-particle interaction is estimated by Van der Waals potential. Simulation results show that under the effect of the rotational component and the extensional component of shear flow, the aggregate simultaneously rotates and changes its outer shape and inner connectivity, then it reaches stable state. Correspondingly, the coordination number varies periodically with the rotation and then approaches a stable value different from the initial one. During the progress toward stable state, the relation between coordination number and volume fraction is independent of shear condition but related to the most compact structure that the aggregate is possible to obtain by restructuring. Such behaviors are observed for different aggregates whose initial structure varies from loose to dense. Moreover, at the stable state, the stable structure is strongly dependent on the applied shear stress and the most compact structure rather than the initial configuration.