Shear-induced criticality near a liquid-solid transition of colloidal suspensions

TL;DR

This study uses numerical experiments to explore how shear flow influences the transition from disordered to ordered phases in colloidal suspensions, revealing critical behavior and phase diagram features.

Contribution

It demonstrates the existence of shear-induced criticality and maps the phase diagram, connecting nonequilibrium shear effects with equilibrium transition points.

Findings

Divergent time scale near transition point

Phase diagram showing transition line and critical region

Critical region vanishes as shear rate approaches zero

Abstract

We investigate colloidal suspensions under shear flow through numerical experiments. By measuring the time-correlation function of a bond-orientational order parameter, we find a divergent time scale near a transition point from a disordered fluid phase to an ordered fluid phase, where the order is characterized by a nonzero value of the bond-orientational order parameter. We also present a phase diagram in the $(\rho, \dot{\gamma}^{\mathrm{ex}})$ plane, where $\rho$ is the density of the colloidal particles and $\dot{\gamma}^{\mathrm{ex}}$ is the shear rate of the solvent. The transition line in the phase diagram terminates at the equilibrium transition point, while a critical region near the transition line vanishes continuously as $\dot{\gamma}^{\mathrm{ex}} \rightarrow 0$.