Restructuring of colloidal aggregates in shear flow: Coupling interparticle contact models with Stokesian dynamics

TL;DR

This paper presents a coupled simulation method combining interparticle contact models with Stokesian dynamics to study how colloidal aggregates restructure under shear flow, revealing compaction behaviors and structural changes.

Contribution

It introduces a novel coupling approach that models both elastic/plastic contacts and hydrodynamic interactions to analyze aggregate restructuring under flow.

Findings

Clusters undergo irreversible compaction under increased shear stress.

Most fractal clusters become rod-shaped packed structures.

Some clusters show isotropic compaction.

Abstract

A method to couple interparticle contact models with Stokesian dynamics (SD) is introduced to simulate colloidal aggregates under flow conditions. The contact model mimics both the elastic and plastic behavior of the cohesive connections between particles within clusters. Owing to this, clusters can maintain their structures under low stress while restructuring or even breakage may occur under sufficiently high stress conditions. SD is an efficient method to deal with the long-ranged and many-body nature of hydrodynamic interactions for low Reynolds number flows. By using such a coupled model, the restructuring of colloidal aggregates under stepwise increasing shear flows was studied. Irreversible compaction occurs due to the increase of hydrodynamic stress on clusters. Results show that the greater part of the fractal clusters are compacted to rod-shaped packed structures, while the others show isotropic compaction.