Recorded presentation4.2
Scaling in geostrophic flow
Harry L. Swinney, University of Texas, Austin, TX; and S. Jung
In 1967 Kraichnan predicted that for two-dimensional turbulence, the dependence of the energy on wavenumber should be given by E(k) ~ k^(-2/3). However, our experiments on nearly two-dimensional (low Rossby number) turbulent flows in a rapidly rotating annulus reveal instead E(k) ~ k^(-2). Measurements with and without a beta plane yield the same scaling. The probability distribution for velocity differences over a distance r exhibits broad non-Gaussian tails as a consequence of the coherent vortices. Surprisingly, the normalized distribution function is self-similar, i.e., independent of r. Our description of the observed vorticity distribution function exploits the underlying Hamiltonian structure of inviscid flows. The predicted distribution function is in good accord with the observations. Recorded presentation
Session 4, Lorenz Symposium IV
Thursday, 13 January 2005, 3:30 PM-5:30 PM
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