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DY: Fachverband Dynamik und Statistische Physik
DY 8: Fluid Physics 2 - organized by Stephan Weiss and Michael Wilczek (Göttingen)
DY 8.2: Vortrag
Montag, 22. März 2021, 11:20–11:40, DYa
Small scale structures of turbulence in terms of entropy and fluctuation theorems — André Fuchs1, •Joachim Peinke1, Matthias Wächter1, Silvio M Durate Queiros2, Alain Girard3, and Pedro G Lind4 — 1ForWind, Inst Physik , University of Oldenburg, — 2Centro Brasileiro de Pesquisas Fisicas and National Institute of Science and Technology for Complex Systems, Rio de Janeiro - RJ, Brazil — 3INAC-SBT, UMR CEA-Grenoble, 38054 Grenoble, France — 4Department of Computer Science, OsloMet - University, N-0130 Oslo, Norway
Experimental evidence that the integral fluctuation theorem as well as a detailed-like fluctuation theorem holds for large entropy values of the turbulent cascade processes. Stochastic equations describing the scale-dependent cascade process are derived. From individual cascade trajectories an entropy term can be determined. The statistical fluctuation theorems set the occurrence of positive and negative entropy events in strict relation, which is consistent with a stochastic description of the turbulence by a Fokker-Planck equation. Most interestingly the entropy concept of cascade trajectories is linked to turbulent structures: Whereas trajectories with entropy- production show expected decreasing behavior; trajectories with entropy-consumption end at small scale at velocity increments with finite size and show a lower bound for small scale increments. This indicates a tendency to local discontinuities in the velocity field. Our current research indicates that the velocity increment dynamics through scales in the cascade process can be described by applying an instanton approach.