Average Patterns of Spatiotemporal Chaos: A Boundary Effect

Chaotic pattern dynamics in many experimental systems show structured time averages. We suggest that simple universal boundary effects underly this phenomenon and exemplify them with the Kuramoto-Sivashinsky equation in a finite domain. As in the experiments, averaged patterns in the equation recover global symmetries locally broken in the chaotic field. Plateus in the average pattern wavenumber as a function of the system size are observed and studied and the different behaviors at the central and boundary regions are discussed. Finally, the structure strenght of average patterns is investigated as a function of system size.