Flow of foam through a convergent channel

Abstract

We study experimentally the flow of a foam confined as a bubble monolayer between two plates through a convergent channel. We quantify the velocity, the distribution and orientation of plastic events, and the elastic stress, using image analysis. We use two different soap solutions: a sodium dodecyl sulfate (SDS) solution, with a negligible wall friction between the bubbles and the confining plates, and a mixture containing a fatty acid, giving a large wall friction. We show that for SDS solutions, the velocity profile obeys a self-similar form which results from the superposition of plastic events, and the elastic deformation is uniform. For the other solution, the velocity field differs and the elastic deformation increases towards the exit of the channel. We discuss and quantify the role of wall friction on the velocity profile, the elastic deformation, and the rate of plastic events.

Simulations of quasi-static foam flow through a diverging-converging channel

“…We use that same geometry here, now with many bubbles. It mirrors recent experimental work (Dollet and Bocher, 2015) in which a foam is made to flow through a diverging channel and the deformation of the foam recorded.…”

“…Moreover, where the bubbles meet they satisfy a particular set of geometric rules, known as Plateau's laws (Plateau, 1873), for example that films always meet in threes at equal angles of 120 • . To study the fundamental aspects of foam flow, we further restrict to the consideration of two-dimensional foams, such as can be made between two parallel sheets of glass (Jones et al, 2013;Dollet and Bocher, 2015). Here, at equilibrium, each film is an arc of a circle, meeting in the afore-mentioned threes.…”

Surface phase transitions in foams and emulsions

“…Several studies showed that the surface viscoelasticity is very important for other foamrelated phenomena as well. Dollet and Bocher [51] showed that the surface viscoelasticity changes qualitatively the dynamic behavior of a bubble monolayer (2D foam) flowing between two solid plates. These results were explained by considering the role of surface viscoelasticity on the bubble-wall friction, bubble elastic deformation, and the rate of bubble plastic rearrangement.…”

Lamella Division in a Foam Flowing through a Two-Dimensional Porous Medium: A Model Fragmentation Process

“…For each site and each fragmentation, we measure the size of the mother bubble and the sizes of the two daughter bubbles, using a procedure described in the Supplementary Materials, which includes Refs. [25][26][27]. We thus recorded a list of 563 mother bubble areas, N frag (a), with a minimum a min and a maximum a max .…”