ECKHAUS INSTABILITY AND DEFECT NUCLEATION IN 2-DIMENSIONAL ANISOTROPIC SYSTEMS

We present an experimental study of the Eckhaus instability and the spatial-temporal evolution of the roll structure in two-dimensional (2D) anisotropic systems. In spite of the fact that the instability in 2D systems is manifested via the nucleation of topological defects, contrary to the case of 1D systems, we find no differences in the basic instability mechanism. Longitudinal, long-wavelength modulation is responsible for the instability, exactly as in 1D systems, and thus the stability boundary and the spatial-temporal evolution dynamics are identical for 1D and 2D roll patterns.