Phase ordering of two-dimensional symmetric binary fluids: A droplet scaling state

The late-stage phase ordering, in d = 2 dimensions, of symmetric fluid mixtures violates dynamical scaling. We show however that, even at 50/50 volume fractions, if an asymmetric droplet morphology is initially present then this sustains itself, throughout the viscous hydrodynamic regime, by a "coalescence-induced coalescence" mechanism. Scaling is recovered (with length scale l ~ t, as in d = 3). The crossover to the inertial hydrodynamic regime is delayed even longer than in d = 3; on entering it, full symmetry is finally restored and we find l ~ t2/3, regardless of the initial state.