Bubbles in sheared two-dimensional foams

Oscillatory shear on two-dimensional monodisperse liquid foams was performed. We show that the effect of the oscillatory shear is to cause the migration of bubbles which size is greater than that of a typical bubble of the foam. These so-called ‘flaws’ move towards the periphery of the foam in a non-random motion, thus realizing size segregation in a system which is by construction gravity-insensitive. We also show that elongated cavities in the foam could be relaxed towards a more isotropic form with oscillatory shear, and we discuss the pertinent parameters of this relaxation.