Regensburg 2016 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 32: Poster - Turbulence

DY 32.2: Poster

Dienstag, 8. März 2016, 18:15–21:00, Poster C

Rotation rate of particle pairs in turbulent flow — •Ali Ghaemi and Abdallah Daddi-Moussa-Ider — Biofluid Simulation and Modeling, University of Bayreuth, Germany

The dynamics of solid particles in turbulent flow plays a key role in many environmental phenomena. For instance, the eruption of volcanoes releases particles with different sizes into the atmosphere which then are transported with turbulent currents. In this work, the statistics of particle pair orientation is numerically studied in homogeneous isotropic turbulent flow. We show that the Kolmogorov picture fails to predict the observed probability density functions (PDFs) of the pair rotation rate and the higher order moments accurately. Therefore, a multifractal formalism is derived in order to include the intermittent behavior that is neglected in the Kolmogorov phenomenology. The PDFs of finding the pairs at a given angular velocity for small relative separations reveals extreme events with stretched tails and high kurtosis values. Furthermore, The PDFs are found to be less intermittent and follow a complementary error function distribution for larger separations.