Virtual Phase Dynamics for Constrained Geometries in a Soap Froth

Soap froths as typical disordered cellular structures, exhibiting spatial and temporal evolution, have been studied through their distributions and topological properties. Recently, persistence has been introduced as a non-topological probe to study froth dynamics at different lengths cales and to view the froth as a two-phase system. Using a direct simulation method, we have investigated virtual phase dynamics in 2D artificial froths with various initial structures corresponding to controlled disorder. In particular, we examine the special case of a defect ring surrounding a central inclusion in a unform froth, for different percentages of persistent cells, where this geomtery permits comparison with shell-theory. It appears that defect location and pattern of cell inclusion in the virtual phase cause considerable variation in the evolutionary Hoaviour, leading t o non-universal exponents for the phase dynamics. This is probably explained by the fact that the froth is still inter transient period over simulation time-scales, rather than achieving the final stage of persistence. However, distinctive patterns of response can be identified for the different froth regions, despite the limitations on system size.