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DY: Fachverband Dynamik und Statistische Physik
DY 8: Fluid Physics 2 - organized by Stephan Weiss and Michael Wilczek (Göttingen)
DY 8.6: Talk
Monday, March 22, 2021, 12:40–13:00, DYa
Lagrangian Turbulence at Unprecedented Reynolds Numbers — •Christian Küchler1,2, Antonio Ibanez Landeta1,2, Jan Molacek1, and Eberhard Bodenschatz1,2,3 — 1Max-Planck-Institute for Dynamics and Self-Organisation, Göttingen, Germany — 2Institute for the Dynamics of Complex Systems of the University of Göttingen, Germany — 3Cornell University, Ithaca, USA
The Lagrangian reference frame, in which turbulence is viewed by tracking fluid elements over time, is the natural framework for studying transport and mixing phenomena (Sawford (2001)) and previously unexplored properties of turbulence (Toschi & Bodenschatz (2009)). Particularly important Lagrangian dynamics occur at large Reynolds numbers, e.g. the formation of clouds and precipitation. To our knowledge, the Variable Density Turbulence Tunnel (Bodenschatz et al. (2014)) is the only apparatus capable of generating turbulence at Taylor-scale Reynolds numbers up to 6000, while permitting Lagrangian measurements. In addition, the turbulence generation is highly adjustable through a uniquely flexible active grid (Griffin et al. (2019)) and by tuning the pressure of the working fluid SF6 up to 15 bar. Here we present the first measurements of Lagrangian particle tracking in this high-pressure environment. We describe the particle injection mechanism, the high-speed camera setup, and the illumination system. We present initial results of particle accelerations at Reynolds numbers greater than 3000, marking the highest Reynolds numbers at which such statistics have ever been recorded. Finally, we provide an outlook on the overall capabilities of the setup.