Growth of disorder about point defects in a two-dimensional foam

The evolution about isolated point defects of various kinds in two-dimensional liquid foam has been studied experimentally. As the foam about the defect coarsens it becomes disordered, the degree of disorder growing with time. This is broadly in line with recent simulations of defects in two-dimensional froths. The limitations on this comparison with theory are discussed. In the case of multiple dislocations in the foam the evolution leads ultimately to a decrease in disorder, which may be relevant to the changes found in the approach of relatively ordered soap froths to a scaling state. Tests of various topological correlations for the disordered foam about the defects suggest that it does not achieve statistical equilibrium during the experiments.