SPATIOTEMPORAL CHAOS IN A MODEL OF RAYLEIGH-BENARD CONVECTION

We present a numerical investigation of mean-flow induced spiral turbu lence in a generalized Swift-Hohenberg model in two dimensions. We sho w the existence of a spatiotemporal chaotic state comprised of a large number of rotating spirals in a large aspect ratio system. This state is not predicted by classical theory. We calculate the spatial correl ation functions for the order parameter, vorticity, and mean-flow held in order to characterize more quantitatively the spiral chaos state. Our simulations show that there is a power-law behavior in the tempora l dynamics of spiral defect chaos. Our study suggests that this spiral defect state occurs for low Prandtl numbers and large aspect ratios. We use as global variables the spectra entropy and the magnitude of th e vorticity to characterize the transition from the global parallel ro ll state to the localized spiral state. Unfortunately we cannot determ ine whether this transition is gradual or sharp.