Regensburg 2010 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 24: Turbulence and wind energy

DY 24.7: Talk

Thursday, March 25, 2010, 11:30–11:45, H47

Anomalous Region in Fractal Flows — •Stefan Weitemeyer¹, Joachim Peinke¹, and Christos Vassilicos² — ¹ForWind, University of Oldenburg, Institute of Physics, Germany — ²Imperial College, Department of Aeronautics, London, UK

Fractal grids produce high turbulence intensities and high Reynolds numbers.

Using different fractal grids in four different wind tunnels, we studied by hot wire measurements which grid parameters determine the properties of the flow behind the grid. We focused on a region close to the grid where the flow is intermittent and carried out statistical analyses. Flatness values much higher than three and skewness values below zero both reflect the presence of highly energetic bursts in this region. Furthermore we studied the two-point correlations and found the flow to be intermittent on all scales. In our current research we want to determine if the flow behind the fractal grid is a superposition of ’classical grid flows’ or if the fractal structure of the grid creates a completely different kind of flow.