Hydrodynamic interactions of colloidal spheres under shear flow

TL;DR

This study uses multiparticle-collision dynamics simulations to analyze how hydrodynamic interactions influence colloidal spheres in shear flow, successfully replicating experimental results and explaining discrepancies with existing theories.

Contribution

It introduces a simulation approach that captures hydrodynamic interactions of colloids under shear, aligning with experiments despite simplified modeling assumptions.

Findings

Simulation reproduces experimental data on colloidal interactions.

Hydrodynamic effects explain differences from theoretical models.

Simplified coupling captures key dynamics of colloidal suspensions.

Abstract

Particles that are immersed in a fluid exchange momentum via the fluid, hence their Brownian motion is correlated. By means of multiparticle-collision dynamics simulations we study the interactions between two colloidal beads in a sheared fluid suspension. Recently, this topic has been addressed in experiments on colloidal particles trapped by optical tweezers in a microfluidic device [PRL, 103, 230602 (2009)] and theoretically by means of a Langevin model [Eur. Phys. J E, 33, 313 (2010)]. Although we neglect the rotational degrees of freedom of the colloids, and employ a very simple coupling between the colloids and the flow field, we can reproduce the experimental data and partly explain why it differs from theory.