Quantitative imaging of concentrated suspensions under flow

TL;DR

This paper reviews recent advances in confocal microscopy techniques for quantitatively imaging the flow of concentrated suspensions at the single-particle level, linking microscopic dynamics to bulk rheological behavior.

Contribution

It provides a comprehensive overview of experimental methods and insights into microscopic flow phenomena in concentrated suspensions, highlighting recent progress in the field.

Findings

Confocal microscopy enables detailed visualization of suspension flow at the particle level.

Microscopic dynamics are closely related to rheological phenomena like yielding and shear localization.

Quantitative imaging improves understanding of suspension flow mechanisms.

Abstract

We review recent advances in imaging the flow of concentrated suspensions, focussing on the use of confocal microscopy to obtain time-resolved information on the single-particle level in these systems. After motivating the need for quantitative (confocal) imaging in suspension rheology, we briefly describe the particles, sample environments, microscopy tools and analysis algorithms needed to perform this kind of experiments. The second part of the review focusses on microscopic aspects of the flow of concentrated model hard-sphere-like suspensions, and the relation to non-linear rheological phenomena such as yielding, shear localization, wall slip and shear-induced ordering. Both Brownian and non-Brownian systems will be described. We show how quantitative imaging can improve our understanding of the connection between microscopic dynamics and bulk flow.