Experiment (left) and CPM simulation (right) of air injection shear banding of foam flowing from left to right in 2D Hele Shaw cell. Air injected in the middle of the cell inflates bubbles leading to a channel of large bubbles. Interplay between shear strain and differential friction determine the channel width and velocity relative to the background flow.
Foam
I study properties of 2-dimensional foams through experiment and simulation. With an REU student, Rebecca Perry, I investigated a novel shear banding phenomenon that helps differentiate various sources of dissipation in flowing foams, such as the relative dissipation rate from soap films moving against glass vs. moving against other soap films. A simple theory explains the observed relationship between channel size and flow rate (Perry, Balter, Glazier, in prep). My numerical simulations of this phenomenon that will be part of a future publication.
Foams are ubiquitous materials with wide-ranging industrial applications. They are interesting in terms of their particular physics and chemistry, and also as model complex fluids. In a 2D foam, i.e. one layer of bubbles between two flat surfaces (usually glass plates), the bubbles are reduced to polygonal regions bounded by parallel soap films. As this foam flows and evolves one can easily track individual soap films, which is not possible in 3D foams. Imaging processing algorithms I developed with Ms. Perry, will allow me to use images from our experiments as initial conditions for simulations. Comparing results from experiment and simulation will provide a way to calibrate our foam simulation method (again, the CPM) and also provide a test bed for a new method I am developing for driving Monte Carlo simulations of nonequilibrium systems.