CHARACTERIZATION OF DISPERSIVE CHAOS AND RELATED STATES OF BINARY-FLUID CONVECTION

We describe an extensive series of experiments on traveling-wave convection in an ethanol/water mixture with separation ratio psi = -0.020 in a long, narrow, annular container. As the stress parameter is quasi-statically increased through the range 0-2% above onset, this system evolves through a series of complex spatiotemporal states before settling into an extended pattern of steady, spatially-uniform convective rolls. Much of the dynamical behavior is influenced by strong nonlinear dispersion, which causes the repeated and often irregular appearance and sudden collapse of spatially-localized bursts of traveling waves. Small-amplitude states seen very close to onset are analyzed quantitatively using a complex Ginzburg-Landau equation. Complex dynamical states encountered further above onset are analyzed using a number of classical statistical techniques, focusing mainly on correlation functions and Fourier spectra. In addition, we use the technique of biorthogonal decomposition in an effort to extract the basic structures of the patterns and to characterize the complexity of their dynamics.