Dresden 2006 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 23: Statistical Physics (general) II
DY 23.2: Vortrag
Dienstag, 28. März 2006, 12:00–12:15, SCH 251
Small Scale Anisotropy in Lagrangian Turbulence — •Eberhard Bodenschatz 1,2, Nicholas Ouellette2, Haitao Xu2, and Mickael Burgoin2 — 1MPI for Dynamics and Self-Organization, Goettingen — 2Cornell University, Ithaca, NY
Intense turbulence is generally assumed to be statistically isotropic at small length and time scales regardless of the symmetries of the large scale flow. We have studied the effects of large scale anisotropy on small scale turbulent fluctuations via the second order Lagrangian velocity structure function and the Lagrangian velocity spectrum in an intensely turbulent laboratory flow using three dimensional optical particle tracking. We find that the asymmetries of the large scale flow are reflected in small scale statistical quantities, though with no change of the scaling exponents. In addition, we present new measurements of the Lagrangian structure function scaling constant $C_0$, which is of central importance to stochastic turbulence models as well as to the understanding of turbulent pair dispersion and scalar mixing, from both the structure function and the spectrum, and the two measurements are shown to agree. The scaling of $C_0$ with the turbulence level is also investigated, and found to be in agreement with an existing model.