Spinodal Decomposition under Shear: Towards a Two-Dimensional Growth

We have studied the interaction of an external flow with the capillary flows that drive the phase separation of a two-fluid system undergoing spinodal decomposition. Here the growing domains are interconnected. Their highly anisotropic correlations have been studied through light scattering techniques simultaneously in two orthogonal directions. In the presence of a shear flow, only two characteristic growth lengths are found, with a time dependence exhibiting unexpected features. In particular in the direction perpendicular to the flow and to the shear, the characteristic length is nearly insensitive to the shear and is identical to that obtained without shear flow. The observations suggest a dimensional reduction of the growth process.