Experiments on Patterns and Noise in Hydrodynamic Systems

Abstract

There is a close relationship between the spatial structure of hydrodynamic flows and the onset of chaos in these systems. In this lecture, I describe this relationship in the context of three experiments (1). Competing patterns or modes of oscillation of the free surface of a fluid layer give rise to chaotic time evolution that can be explained by a relatively simple model (2). Competing spatial periodicities in the electrohydrodynamics of a layer of nematic liquid crystal give rise to commensurate, incommensurate, and apparently spatially chaotic phases (3). New experiments on the evolution of Rayleigh-Bénard convection patterns provide a test of models in which a functional of a two-dimensional order parameter field evolves toward a minimum. Since this work has been or will be reported in detail elsewhere, we give only a brief summary here with references to the original work.