Vortex statistics in turbulent rotating convection

Kunnen, Rudie; Clercx, Hjh Herman; Geurts, BJ Bernard

doi:10.1103/physreve.82.036306

Cited by 45 publications

(44 citation statements)

References 30 publications

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“…This would help explain the colder fluctuations in the bottom boundary layer. Recently, however, new velocity measurements [41] suggest that the experimental evidence for core suction is an artifact of low spatial resolution. Whether there is core suction or not, Ekman pumping must be sufficiently robust to thin the boundary layer significantly in the vicinity of the vortex, thereby depleting the boundary layer locally and allowing cooler fluid to vertically penetrate the BL region.…”

Section: A Bulk Temperature: Fluctuations and Mean Gradientmentioning

confidence: 99%

Local temperature measurements in turbulent rotating Rayleigh-Bénard convection

Liu

Ecke

2011

Phys. Rev. E

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We present local temperature measurements of turbulent Rayleigh-Bénard convection with rotation about a vertical axis. The fluid, water with Prandtl number about 6, was confined in a cell with a square cross section of 7.3 × 7.3 cm 2 and a height of 9.4 cm. Temperature fluctuations and boundary-layer profiles were measured for Rayleigh numbers 1 × 10 7 < Ra < 5 × 10 8 and Taylor numbers 0 < Ta < 5 × 10 9 . We present statistics of the temperature field measured by a single thermistor located along the vertical centerline of the cell or by an array of thermistors distributed laterally from that centerline. The statistics include the mean temperature, standard deviation, skewness, and the probability distribution functions at various locations in the cell, especially near and inside the thermal boundary layer. The effects of rotation on these quantities are discussed including the presence of a rotation-dependent mean vertical temperature gradient, the negative skewness of temperature fluctuations in the boundary layer, and the horizontal homogenization of temperature.

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Section: A Bulk Temperature: Fluctuations and Mean Gradientmentioning

confidence: 99%

Local temperature measurements in turbulent rotating Rayleigh-Bénard convection

Liu

Ecke

2011

Phys. Rev. E

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“…For Ek 1.8·10 −4 rotation starts to play an important role, due to the development of vertically aligned vortical plumes [7,8]. The length scale of these vortical structures, L, is known to decrease with increasing rotation rate [38,39]. This decrease is moreover expected to scale as L ∼ Ek 1/3 [40,41].…”

Section: B Rotating Turbulencementioning

confidence: 99%

Geometry of tracer trajectories in rotating turbulent flows

et al. 2017

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The geometry of passive tracer trajectories is studied in two different types of rotating turbulent flows; rotating Rayleigh-Bénard convection (RBC; experiments and direct numerical simulations) and rotating electromagnetically forced turbulence (EFT; experiments). This geometry is fully described by the curvature and torsion of trajectories and from these geometrical quantities we can subtract information on the typical flow structures at different rotation rates. Previous studies, focusing on non-rotating homogeneous isotropic turbulence (HIT), show that the probability density functions (PDFs) of curvature and torsion reveal pronounced power laws. However, the set-ups studied here involve inhomogeneous turbulence and in RBC the flow near the horizontal plates is definitely anisotropic. We want to investigate how the typical shapes of the curvature and torsion PDFs, including the pronounced scaling laws, are influenced by this level of anisotropy and inhomogeneity and how this effect changes with rotation. A first effect of rotation is observed as a shift of the curvature and torsion PDFs towards higher values in the case of RBC and towards lower values in the case of EFT. This shift is related to the length scale of typical vortical structures that decreases with rotation in RBC, but increases with rotation in EFT, explaining the opposite shifts of the curvature (and torsion) PDFs. A second remarkable observation is that in RBC the HIT scaling laws are always recovered, as long as the boundary layer (BL) is excluded. This suggests that these scaling laws are very robust and hold as long as we measure in the turbulent bulk. In the BL of the RBC cell, however, the scaling deviates from the HIT prediction for lower rotation rates. This scaling behavior is found to be consistent with the coupling between the boundary layer dynamics and the bulk flow, that changes under rotation. In particular, it is found that the active coupling of the Ekman-type boundary layer with the bulk flow suppresses anisotropy in the BL region for increasing rotation rates.

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“…A number of previous studies have considered rotating turbulent convection and the formations of convection-scale vortices (e.g., Bubnov and Golitsyn 1986;Chen et al 1989;Vorobieff and Ecke 2002;Kunnen et al 2010), and rotating convective mixed layers especially in geophysical flows (e.g., Fernando et al 1989;Fernando et al 1991;Mironov et al 2000;Wang 2006). Among these studies, Chen et al (1989) performed a laboratory experiment in which a homogeneous rotating fluid was heated uniformly from the bottom, where one of their interests was strong cyclonic vertical vortices of convection-scale that were formed in a convective mixed layer in a rotating system.…”

Section: Introductionmentioning

confidence: 99%