Hydrodynamic effects in phase separation: An explicit solution approach

摘要

We study the influence of hydrodynamic modes on phase separation by modeling pure-phase domains with kinks. The velocity field, determined adiabatically in terms of the thermodynamic source, describes a steady state compressible flow. We consider spherical, columnar, and disklike domains. In the former two cases, we obtain crossover from the (R) over dot similar to 1/R-2 law to the R similar to t law as in the incompressible case. The growth of columnar domains is dominated by hydrodynamics, while for spherical domains we find competition between hydrodynamics and particle diffusion: this competition determines a threshold in size for the fluctuations, i.e., only large enough fluctuations can initiate the spinodal decomposition. We finally study disklike domains in a quasi-two-dimensional system and obtain, for small radii, the growth law (R) over dot similar to 1/[R(3)ln(Lambda/R)], while for large radii (R) over dot similar to 1/[R(2)ln(Lambda/R)]. We find that stable microdomains can be formed, whose size is fixed by the thickness of the lamella and by the parameters of the fluid (e.g., viscosity, transport coefficient, etc.).