Chaotic Diffusion of Localized Turbulent Defect and Pattern Selection in Spatiotemporal Chaos

Coupled-map lattices are investigated as a model for the spatiotemporal chaos. Patterns with some wavelengths are selected through a chaotic motion of domain boundaries. Localized defect which separates two domains with antiphase is found. It changes chaotically in time and moves randomly in space. The diffusion coefficient and Kolmogorov-Sinai entropy of a defect are calculated. A novel phase transition at the collapse of a pattern is studied in connection with a crisis in a high-dimensional dynamical system.