Foams in a rotating drum

TL;DR

This study investigates the behavior of a two-dimensional foam in a rotating Hele-Shaw cell, analyzing liquid fraction, interface deformation, shear profiles, and rheological properties to understand foam dynamics under rotation.

Contribution

It introduces a semiempirical model for foam velocity profiles in a rotating cell, highlighting viscous dissipation effects between bubbles and walls.

Findings

Liquid fraction increases with rotation

Foam interface deforms during rotation

Effective viscosity is determined from shear profiles

Abstract

A nearly two-dimensionnal foam is generated inside a Hele-Shaw cell half-filled with a surfactant solution. The cell is then placed vertically on a tumbler so that it rotates around its center with the cell angular velocity as the control parameter. During the foam rotation the liquid fraction increases and the foam/liquid interface deforms. The shear velocity profiles generated inside the foam are studied along two representative lines. The foam rheological properties are obtained using statistical tools and allow us to determine the foam effective viscosity. A semiempirical model is proposed for these velocity profiles, emphasizing the significance of the viscous dissipations between the bubbles and with the cell walls.