Berlin 2018 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 19: Extreme Events

DY 19.3: Talk

Monday, March 12, 2018, 18:00–18:15, BH-N 333

Extrem Velocity Fluctuations in Turbulence Characterised as Negative Entropy Events — Andre Fuchs¹, Nico Reinke¹, Daniel Nickelsen², Matthias Wächter¹, and •Joachim Peinke¹ — ¹Institute of Physics, Carl von Ossietzky University of Oldenburg, Germany — ²Institute of Theoretical Physics, University of Stellenbosch, South Africa

The turbulent cascade is analysed with respect to the evolution process of velocity increments towards smaller scales. A general n-point description is achieved by means of Markow process in the scale. Finally we set up Fokker-Planck equation for the cascade. Based in this description entropies values S_i can be assigned to all velocity fluctuations. These fluctuating entropy values fulfil integral fluctuation theorem, claiming that <exp(−S_i)>=1. As a main finding we see that negative entropies events are linked to localised extrem velocity fluctuations on small scales.