Dynamics of a shear-induced aggregation process by a combined Monte Carlo-Stokesian Dynamics approach

In the present work we investigated the collision efficiency of colloidal aggregates suspended in a shear flow. A Discrete Element Method (DEM), built in the framework of Stokesian Dynamics, was developed to model hydrodynamic and colloidal interactions acting on each primary particle composing the aggregates. Aggregates with complex geometries were generated by means of a combined DEM-Monte Carlo algorithm able to reproduce a shear-induced aggregation process occurring in a dilute colloidal suspension. Simulations, involving pairs of aggregates, were conducted according to a grid-based technique, in order to evaluate collision efficiencies. Size disproportion between aggregates and morphology shape anisotropy emerged as the principal causes affecting collision efficiencies. This work constitutes a first attempt to extend the traditional Von Smoluchowski’s theory of shear-induced coagulation of spherical particles to the case of randomly-structured aggregates.