Inhomogeneous steady shear dynamics of a three-body colloidal gel former

TL;DR

This study uses adaptive Brownian dynamics simulations to explore how a three-body colloidal gel responds to inhomogeneous shear forces, revealing complex flow and structural behaviors driven by superadiabatic forces.

Contribution

It introduces a detailed simulation analysis of inhomogeneous shear flow in a three-body colloidal gel and validates a power functional theory for viscous forces.

Findings

Particles accumulate in quiescent or flow regions depending on shear magnitude

Flow and structure are driven by viscous and superadiabatic forces

Power functional theory accurately reproduces viscous force profiles

Abstract

We investigate the stationary flow of a colloidal gel under an inhomogeneous external shear force using adaptive Brownian dynamics simulations. The interparticle forces are derived from the Stillinger-Weber potential, where the three-body term is tuned to enable network formation and gelation in equilibrium. When subjected to the shear force field, the system develops remarkable modulations in the one-body density profile. Depending on the shear magnitude, particles accumulate either in quiescent regions or in the vicinity of maximum net flow, and we deduce this strong non-equilibrium response to be characteristic of the gel state. Studying the components of the internal force parallel and perpendicular to the flow direction reveals that the emerging flow and structure of the stationary state are driven by significant viscous and structural superadiabatic forces. Thereby, the magnitude and nature of the observed non-equilibrium phenomena differs from the corresponding behavior of simple fluids. We demonstrate that a simple power functional theory reproduces accurately the viscous force profile, giving a rationale of the complex dynamical behavior of the system.