Decorrelating a compressible turbulent flow: an experiment.
Floating particles that are initially distributed uniformly on the surface of a turbulent fluid, subsequently coagulate, until finally a steady state is reached. This being so, they manifestly form a compressible system. In this experiment, the information dimension D1, and the Lyapunov exponents of the coagulated floaters, is measured. The trajectories and the velocity fields of the particles are captured in a sequence of rapidly acquired images. Then the velocity sequence is randomly shuffled in time to generate new trajectories. This analysis mimics the Kraichnan ensemble and yields properties of a velocity correlation function that is delta correlated in time (but not in space). The measurements are compared with theoretical expectations and with simulations of Boffetta , that closely mimic the laboratory experiment reported here.
Larkin
Jason
J
Department of Physics & Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA. jml37+@pitt.edu
Goldburg
Walter I
WI