The Search for Exact Coherent Structures in a Quasi-Two-Dimensional Flow
Abstract
Recent
theoretical advances suggest that turbulence can be characterized using
unstable solutions of the Navier-Stokes equations having regular temporal
behavior, called Exact Coherent Structures (ECS). Due to their experimental
accessibility and theoretical tractability, two-dimensional flows provide an
ideal setting for the exploration of turbulence from a dynamical systems
perspective. In our talk, we present a combined numerical and experimental
study of electromagnetically driven flows in a shallow layer of electrolyte.
On the numerical front we present our research concerning the search for ECS
in a two-dimensional Kolmogorov-like flow. We discuss the change in the
dynamics of the flow as the Reynolds number is varied. For a weakly turbulent
flow, we show that the turbulent trajectory explores a region of state space
which contains a number of ECS. We then discuss the occurrence of states
similar to these numerically computed ECS in an experimental
quasi-two-dimensional Kolmogorov-like flow.