Berlin 2008 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 17: Poster I
DY 17.57: Poster
Dienstag, 26. Februar 2008, 16:00–18:00, Poster C
A Comparison of Turbulent and Random Fields — •Michael Wilczek1, Holger Homann2, Rainer Grauer2, and Rudolf Friedrich1 — 1Institute for Theoretical Physics, Westfälische Wilhelms-Universität Münster, Germany — 2Institute for Theoretical Physics I, Ruhr-Universität Bochum, Germany
Fully developed turbulence is dominated by a complex tangle of vortex filaments. During their complicated interaction they produce an almost Gaussian velocity field and an energy spectrum according to Kolmogorov's classical prediction. By a randomization procedure we construct random, incoherent fields, which maintain these properties but lack of any signatures of coherent structures. Regarding Eulerian statistics a comparison of the coherent and incoherent fields reveals significant differences in one-point statistics like the pdf of vorticity, velocity and acceleration. An investigation of the statistical alignment of these fields confirms the picture of turbulence as an ensemble of tubular coherent structures. A comparison of the Eulerian structure function gives further insight to the relation between coherent structures and intermittency. Additionally we study the advection of tracer particles, focusing on Lagrangian structure functions. We find that the scaling properties significantly differ in both cases, consistent with the observations in the Eulerian frame.