A Molecular Hydrodynamic Theory of Supercooled Liquids and Colloidal Suspensions under Shear

TL;DR

This paper extends mode-coupling theory to describe supercooled liquids and colloidal suspensions under steady shear, revealing how shear flow accelerates structural relaxation.

Contribution

It develops a nonlinear hydrodynamic model for the intermediate scattering function under shear, bridging theory with recent simulation results.

Findings

Structural relaxation time decreases with shear rate as a power law.

Qualitative agreement with molecular dynamics simulations.

Provides physical insights into shear-induced dynamics.

Abstract

We extend the conventional mode-coupling theory of supercooled liquids to systems under stationary shear flow. Starting from generalized fluctuating hydrodynamics, a nonlinear equation for the intermediate scattering function is constructed. We evaluate the solution numerically for a model of a two dimensional colloidal suspension and find that the structural relaxation time decreases as $\dot{\gamma}^{-\nu}$ with an exponent $\nu \leq 1$, where $\dot{\gamma}$ is the shear rate. The results are in qualitative agreement with recent molecular dynamics simulations. We discuss the physical implications of the results.