Foam rheology : insights from three-dimensional imaging at the bubble scale
Liquid foams are a model system to study the mechanics of amorphous materials and non-Newtonian fluids. I will present our experiments combining rheometry and real-time 3D imaging at the bubble scale, using fast X-ray tomography. This unique set of data provides a full mechanical characterisation of a sheared foam at the bubble scale, including displacements, plastic reorganisation of the network contact between bubbles, and a new measure of the elastic stress tensor [1]. I will discuss the regimes of elastic loading, plastic flow, and relaxation after shear cessation. Our results help clarifying the tensorial response of yield-stress fluids beyond simple shear, the validity of recent elastoplastic models, and the origin of residual stress in amorphous materials. If time allows, I will briefly touch upon my other current research activities (gas transfers through foams, plant-inspired flows in microfluidic channels, acoustic imaging using bubbles, liquid damping by contact line friction).
Left : three-dimensional image of a liquid foam inside a plate-plate rheometer. Right : labelling of each individual bubble in this foam.
Contact Nathanaël Machicoane for more information or to schedule a discussion with the seminar speaker.