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DY: Fachverband Dynamik und Statistische Physik

DY 4: Fluid Physics and Turbulence

DY 4.3: Talk

Monday, March 18, 2024, 10:15–10:30, BH-N 128

Ensemble modeling of large-scale intermittency in turbulence — •Lukas Bentkamp and Michael Wilczek — Theoretical Physics I, University of Bayreuth, Germany

Turbulent flows at high Reynolds number are often assumed to have universal small-scale statistics, independent of the precise structure of the large scales. However, many experimental and numerical studies show a large scatter of statistical quantities, in particular with respect to higher-order moments. One reason for this may be large-scale intermittency, i.e. very slow variations of the large scales whose effect is still detectable at the small scales. At the example of homogeneous, isotropic turbulence simulations with sinusoidally varying energy injection rate, we investigate how ensembles of statistically stationary flows can be used to model the impact of large-scale intermittency. In order to build an accurate ensemble model, we find that not only the time series of the mean energy dissipation rate but also statistical fluctuations around it have to be incorporated.

Keywords: Turbulent flows; Intermittency; Direct numerical simulation; Modeling