15th European Turbulence Conference 2015
August 25-28th, 2015, Delft, The Netherlands
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Investigation of a flow field generated by a fractal grid based on experimental data and CFD simulations


Go-down etc15 Tracking Number 303

Presentation:
Session: Control 3
Room: Room D
Session start: 10:30 Wed 26 Aug 2015

AndrĂ© Fuchs   andre.fuchs@uni-oldenburg.de
Affifliation: ForWind, Institute of Physics, University of Oldenburg, Oldenburg, Germany

Wided Medjroubi   wided.medjroubi@uni-oldenburg.de
Affifliation: ForWind, Institute of Physics, University of Oldenburg, Oldenburg, Germany

Nico Reinke   nico.reinke@uni-oldenburg.de
Affifliation: ForWind, Institute of Physics, University of Oldenburg, Oldenburg, Germany

Gerd Guelker   gerd.guelker@uni-oldenburg.de
Affifliation: ForWind, Institute of Physics, University of Oldenburg, Oldenburg, Germany

Joachim Peinke   peinke@uni-oldenburg.de
Affifliation: ForWind, Institute of Physics, University of Oldenburg, Oldenburg, Germany


Topics: - Control of turbulent flows, - Intermittency and scaling, - Jets and wakes

Abstract:

Fractal grids generate turbulence by directly exciting many length-scales of different sizes simultaneously, rather than using the nonlinear cascade mechanism to obtain multiscale excitation, as it is the case for classical grids. These scales influence each other and show very different properties compared to all previously documented turbulent flows. In this work we present experimental wind tunnel and computer fluid dynamics (CFD) studies of the turbulent flow generated by a fractal grid under the same conditions. We did an extensive statistical study and a direct comparison between the experimentally and numerically acquired time series in order to investigate and compare one-point- and two-point-statistics. In addition we present an application of a stochastic method, so-called Langevin approach, to the experimentally and numerically acquired velocity increment time series to examine three-point-statistics in terms of Kramers-Moyal coefficients.