HYDRODYNAMIC INTERFACE QUENCH EFFECTS ON SPINODAL DECOMPOSITION FOR SYMMETRICAL BINARY-FLUID MIXTURES

For nearly symmetric binary fluid mixtures, the coupling between concentration and velocity fields leads to a quick hydrodynamic coarsening: For bicontinuous phase separation, the pattern evolution is known to be governed by tube hydrodynamic instability. The interface tension is a driving force in the hydrodynamic coarsening. In the conventional theories of late-stage phase separation, local equilibrium has so far been assumed; however, this assumption might not be valid for nearly symmetric fluid mixtures even after the formation of a sharp interface. This is because the interfacial tension probably starts to play a major role in coarsening before the concentration reaches the local equilibrium concentration. In such a case, there is a possibility that the concentration diffusion cannot follow this quick geometrical coarsening. This could cause a drastic effect, which we call an interface quench effect. The interface quench effect could induce spontaneous double phase separation for bicontinous morphology, especially under a geometrical confinement. © 1995 The American Physical Society.