Berlin 2015 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 32: Focus Session: Statistics of fully developed turbulence
DY 32.6: Hauptvortrag
Mittwoch, 18. März 2015, 16:45–17:15, BH-N 243
Particle motion and irreversibility of turbulent flows — •Alain Pumir1,2, Haitao Xu2, Jennifer Jucha2, and Eberhard Bodenschatz2 — 1Laboratoire de Physique, Ecole Normale Superieure de Lyon, F-69007, Lyon, France — 2Max-Planck Institut für Dynamik und Selbst-Organisation, D-37077, Göttingen, Germany
In three-dimensional turbulent flows, the flux of energy from large to small scales breaks time- reversal symmetry. I will discuss how this irreversibility can be observed by following the trajec- tories of tracers, moving with the fluid.
For the problem of relative particle dispersion, irreversibility implies that particles separate slower forward in time than backward (see Jucha et al, PRL 2014). This property can be understood in terms of an exact relation, established directly from the Navier-Stokes equations. A more surprising observation is that a tracer particle needs more time to build up large kinetic energy, than to dissipate it. This allows us to quantify the irreversibility of the turbulent fluid (Xu et al, PNAS, 2014).