SHEAR-FLOW EFFECTS ON A CRITICAL BINARY MIXTURE DURING PHASE-SEPARATION

The effects of a shear flow on growth during phase separation of liquids are investigated. A light scattering study is performed during the spinodal decomposition of a critical binary mixture (water-isobutyric acid) under a Couette flow. Three orthogonal planes are studied in the Fourier space. We find that even a very weak shear can markedly affect the separation process, producing both an anisotropic growth and an unexpected loss of correlation between domains in only one direction. The comparison with a numerical simulation where only the deformation is taken into account enables the flow effects to be separated from growth. In the stretching direction, a scaled function of growth that depends on temperature, time and shear rate is proposed. It is seen to fit the data well.