Three-dimensional foam flow resolved by fast X-ray tomographic microscopy

¹ Université Nice Sophia Antipolis, CNRS, LPMC, UMR 7336 - Parc Valrose, 06100 Nice, France
² Institut de Physique de Rennes, UMR CNRS 6251, Université de Rennes 1, Campus de Beaulieu 35042 Rennes Cedex, France
³ Institute for Biomedical Engineering, University and ETH Zurich - Gloriastrasse 35, Zurich, Switzerland
⁴ Swiss Light Source, Paul Scherrer Institute - Villigen, Switzerland
⁵ Laboratoire de Physique, ENS Lyon, UMR CNRS 5672 - 46 allée d'Italie, 69007 Lyon, France

Received: 17 June 2015
Accepted: 27 July 2015

Abstract

Adapting fast tomographic microscopy, we managed to capture the evolution of the local structure of the bubble network of a 3D foam flowing around a sphere. As for the 2D foam flow around a circular obstacle, we observed an axisymmetric velocity field with a recirculation zone, and indications of a negative wake downstream the obstacle. The bubble deformations, quantified by a shape tensor, are smaller than in 2D, due to a purely 3D feature: the azimuthal bubble shape variation. Moreover, we were able to detect plastic rearrangements, characterized by the neighbor swapping of four bubbles. Their spatial structure suggests that rearrangements are triggered when films faces get smaller than a characteristic area.