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DY: Fachverband Dynamik und Statistische Physik
DY 8: Fluid Physics 2 - organized by Stephan Weiss and Michael Wilczek (Göttingen)
DY 8.4: Talk
Monday, March 22, 2021, 12:00–12:20, DYa
Velocity measurements in rotating Rayleigh-Bénard convection and the Boundary Zonal Flow — Marcel Wedi1, •Denis Funfschilling2, and Stephan Weiss1 — 1Max-Planck-Institute for Dynamics and Self-Organization, Göttingen, Germany — 2Université Strasbourg, France
Rotating turbulent thermal convection is of great importance in various astro- and geophysical systems, where the buoyancy driven flow strongly influenced by Coriolis forces due to rotation of the celestial bodies. It has been studied for decades in the so-called Rayleigh-Bénard setup, where a horizontal fluid layer is heated at the bottom and cooled at the top and rotated around the vertical axis. We investigate the horizontal velocity field using 2D-particle image velocimetry (PIV) in a cylindrical cell (H=196 mm high) with aspect ratio Γ=D/H=1. We use water and various water-glycerol mixtures as working fluid resulting in a Prandtl number (Pr) in the range 6≤ Pr≤70 and Rayleigh numbers (Ra) 108 < Ra < 2× 109. With our rotating table we reach Ek as low as 10−5. We are mainly interested in studying the recently discovered Boundary Zonal Flow (BZF, see Zhang et al., Phys.Rev.Lett. 2020). The BZF is observed in a region close to the lateral sidewall with a cyclonic flow, i.e, a positive mean azimuthal velocity that is separated from and anticyclonic bulk, with negative mean azimuthal velocity. We measure the size of the BZF as a function of Ek and Ra, and compare the results with DNS (Zhang and Shishkina, 2020).