Greifswald 2009 – scientific programme
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EP: Fachverband Extraterrestrische Physik
EP 7: Poster Session Extraterrestrics
EP 7.3: Poster
Tuesday, March 31, 2009, 17:30–19:00, Foyer der Zahnklinik
Bridging Eulerian and Lagrangian fluctuations — •Christian Schwarz1, Christoph Beetz1, Oliver Kamps2, Rudolf Friedrich2, Jürgen Dreher1, and Rainer Grauer1 — 1Theoretische Physik I, Ruhr-Universität Bochum, Germany — 2Theoretische Physik, Universität Münster, Germany
Compressible turbulent flows as they occur in the interplanetary medium may be looked at from two different points of view: the Eulerian and the Lagrangian. Understanding the relation between Eulerian and Lagrangian statistics is still an open problem since the most singular structures in turbulence like vortex tubes, current sheets and shocks have a very different impact on Eulerian and Lagrangian PDFs. Based on DNS of compressible Navier-Stokes turbulence, we propose a mapping between the two statistics with two transitional probabilities. The first describes the transition to a semi-Lagrangian equal-time statistics whereas the second has the character of an exit time statistical quantity. If one models the transitional PDFs with delta-functions, an analytical expression for the structure function exponents could be obtained by making use of the Mellin transform. Comparison of the exponents with those obtained from numerical simulations reveals that the modeling must contain a time-lag dependent change of the variance of the transition probabilities.