Slow flows of yield stress fluids: complex spatio-temporal behaviour within a simple elasto-plastic model

TL;DR

This paper introduces a simple athermal elasto-plastic model capturing complex spatio-temporal flow behaviors of dense disordered materials, including bursty plastic events and flow localization near walls, aligning with experimental observations.

Contribution

It presents a minimal model incorporating local plasticity and elastic interactions to explain complex flow phenomena in yield stress fluids, highlighting the role of correlated plastic bursts.

Findings

Flow arises from collective plastic bursts at low shear rates.

Correlation length diverges algebraically as shear rate decreases.

Flow localization occurs near confining walls with intermittent bursts.

Abstract

A minimal athermal model for the flow of dense disordered materials is proposed, based on two generic ingredients: local plastic events occuring above a microscopic yield stress, and the non-local elastic release of the stress these events induce in the material. A complex spatio-temporal rheological behaviour results, with features in line with recent experimental observations. At low shear rates, macroscopic flow actually originates from collective correlated bursts of plastic events, taking place in dynamically generated fragile zones. The related correlation length diverges algebraically at small shear rates. In confined geometries bursts occur preferentially close to the walls yielding an intermittent form of flow localization.