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

Christophe Raufaste (1) , Benjamin Dollet (2) , Kevin Mader (3, 4) , Stéphane Santucci (5) , Rajmund Mokso (3)

1 LPMC - Laboratoire de physique de la matière condensée
2 IPR - Institut de Physique de Rennes
3 SLS-PSI - The Swiss Light Source (SLS)
4 IBT - Institute for Biomedical Engineering [ETH Zürich]
5 Phys-ENS - Laboratoire de Physique de l'ENS Lyon

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.

Domaines: Mécanique des fluides [physics.class-ph]; Matière Molle [cond-mat.soft]; Instrumentations et Détecteurs [physics.ins-det]

Christophe Raufaste, Benjamin Dollet, Kevin Mader, Stéphane Santucci, Rajmund Mokso. Three-dimensional foam flow resolved by fast X-ray tomographic microscopy. EPL - Europhysics Letters, 2015, 111 (3), pp.38004. ⟨10.1209/0295-5075/111/38004⟩. ⟨hal-01192711⟩