Nonlinear Stress Fluctuation Dynamics of Sheared Disordered Wet Foam

TL;DR

This study investigates the stress fluctuation dynamics in sheared disordered wet foam, revealing scale-invariant behavior and a transition in dynamics around a specific shear rate.

Contribution

It provides a comprehensive analysis of stress fluctuations in wet foam across various strain rates and system sizes, highlighting size independence and a critical shear rate transition.

Findings

Stress fluctuations are largely independent of system size.

A transition in stress behavior occurs around 0.07 s^{-1} shear rate.

Stress drop distribution and fluctuation intensity are characterized across conditions.

Abstract

Sheared wet foam, which stores elastic energy in bubble deformations, relaxes stress through bubble rearrangements. The intermittency of bubble rearrangements in foam leads to effectively stochastic drops in stress that are followed by periods of elastic increase. We investigate global characteristics of highly disordered foams over three decades of strain rate and almost two decades of system size. We characterize the behavior using a range of measures: average stress, distribution of stress drops, rate of stress drops, and a normalized fluctuation intensity. There is essentially no dependence on system size. As a function of strain rate, there is a change in behavior around shear rates of $0.07 {\rm s^{-1}}$.