Ageing of free bubble clusters

Abstract The ageing of two-dimensional free foam clusters has been studied experimentally. We have determined the kinetics of coarsening of inner and peripheral bubbles in a cluster, and the respective distributions of area and number of sides as a function of time. The distributions remain stationary at long times when the kinetics are approximately parabolic and the mean sizes of the two types of bubble are the same. The total area of peripheral bubbles remains nearly constant as the cluster shrinks. We also found that Lewis' law applies equally to peripheral and inner bubbles in the cluster.