Bubbles in sheared two-dimensional foams

TL;DR

This study investigates how oscillatory shear causes size-based bubble migration and cavity relaxation in two-dimensional monodisperse foams, revealing non-random bubble segregation and foam shape relaxation mechanisms.

Contribution

It demonstrates bubble size segregation and cavity relaxation in 2D foams under oscillatory shear, highlighting non-gravitational segregation and shape isotropization processes.

Findings

Larger bubbles migrate towards foam edges.

Oscillatory shear induces cavity relaxation towards isotropy.

Size segregation occurs without gravity influence.

Abstract

Oscillatory shear on two-dimensional monodisperse liquid foams was performed. We show that the effect of the oscillatory shear is to cause the migration of bubbles which size is greater than that of a typical bubble of the foam. These so-called flaws move towards the periphery of the foam in a non random motion, thus realizing size segregation in a system which is by construction gravity insensitive. We also show that elongated cavities in the foam could be relaxed towards a more isotropic form with oscillatory shear, and we discuss the pertinent parameters of this relaxation.