Experimental evidence for chaotic scattering in a fluid wake

We present the first experimental evidence of chaotic scattering in a fluid wake. Measurements of tracer particles and dye in the stratified wake of a moving cylinder are shown to be consistent with four predictions based on simple models and direct numerical simulation: unstable periodic orbits were shadowed by tracer particles; streaklines marked by wake-delayed dye are shown to be fractal; early time-delay statistics of fluid elements interacting with the wake decayed exponentially; and finally, the fractal dimension of the wake is consistent with the dynamics of the wake, as measured by characteristic time delays and Lyapunov exponents.