Shear-Induced Stress Relaxation in a Two-Dimensional Wet Foam

TL;DR

This study investigates how a wet, two-dimensional foam relaxes stress under slow shear, revealing elastic behavior, stress drops, and their dependence on shear rate, with implications for foam modeling.

Contribution

It provides experimental data on stress relaxation and flow behavior of 2D wet foam under shear, comparing results with existing foam models.

Findings

Stress drops occur during foam flow under shear.

Stress drop distribution varies with shear rate.

Foam exhibits elastic response before yielding.

Abstract

We report on experimental measurements of the flow behavior of a wet, two-dimensional foam under conditions of slow, steady shear. The initial response of the foam is elastic. Above the yield strain, the foam begins to flow. The flow consists of irregular intervals of elastic stretch followed by sudden reductions of the stress, i.e. stress drops. We report on the distribution of the stress drops as a function of the applied shear rate. We also comment on our results in the context of various two-dimensional models of foams.