Microscopic aspects of Liquid Foam Fracture

A layer of foam bubbles between parallel plates (a quasi-two-dimensional liquid foam) gives unique access to the details of microscopic configurations in a system whose macroscopic properties include both liquid and solid behavior. The failure of cohesion under stress in such a layer of bubbles offers a study case on fracture, which we have experimentally shown to occur both in a mode similar to fluid fingering and a mode similar to the cleavage of a solid material. Simulations elucidate the microscopic aspects and the fluid-dynamical mechanisms behind these processes, spanning a wide variety of length and time scales and incorporating both fracture modes. Aspects of microstructure and rate dependence can thus become part of a detailed study of fundamental fracture processes.