Optimal Prandtl number for heat transfer in rotating Rayleigh–Bénard convection

Stevens, Richard J. A. M.; Clercx, Hjh Herman; Lohse, Detlef

doi:10.1088/1367-2630/12/7/075005

Cited by 62 publications

(86 citation statements)

References 25 publications

(74 reference statements)

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“…A main feature of rotating Rayleigh-Bénard convection with r > 1 is the occurrence of a maximum in the Nusselt number Nu at a specific rotation rate (Liu and Ecke, 1997;Stevens et al, 2010). In fact, at Rossby number % 2:45 and Prandtl number r ¼ 6:4 such a maximum was found at the selected Rayleigh number-this maximum is about 15% larger than the Nusselt number in the nonrotating case (Kunnen, , 2006Stevens et al, 2010). Such an increase in the Nusselt number at appropriate Rossby numbers is due to Ekman pumping, which is efficient only for r > 1 and is gradually reduced once the Rayleigh number is increased .…”

Section: Governing Equations and Numerical Methodsmentioning

confidence: 99%

Intensified heat transfer in modulated rotating Rayleigh–Bénard convection

Geurts

Kunnen

2014

International Journal of Heat and Fluid Flow

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Section: Governing Equations and Numerical Methodsmentioning

confidence: 99%

Intensified heat transfer in modulated rotating Rayleigh–Bénard convection

Geurts

Kunnen

2014

International Journal of Heat and Fluid Flow

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“…11 and 12. At small enough Ro, experiments and direct numerical simulations (DNSs) of the full Navier-Stokes equations (in the Boussinesq approximation) should give similar results as simulations of the asymptotically reduced equations. Up to now, most of the experiments [13][14][15][16][17][18][19][20][21][22][23] and DNSs 16,18,[24][25][26][27] did not reach deep into the rapidly rotating convection regime. The few experimental and numerical studies that entered decisively into this regime 9,[28][29][30] primarily use the overall heat transfer to characterize rapidly rotating Rayleigh-Bénard convection and identify transitions between flow regimes from changes in the heat-flux scaling.…”

Section: Introductionmentioning

confidence: 98%

Exploring the geostrophic regime of rapidly rotating convection with experiments

2017

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Rapidly rotating Rayleigh–Bénard convection is studied using time-resolved particle image velocimetry and three-dimensional particle tracking velocimetry. Approaching the geostrophic regime of rotating convection, where the flow is highly turbulent and at the same time dominated by the Coriolis force, typically requires dedicated setups with either extreme dimensions or troublesome working fluids (e.g., cryogenic helium). In this study, we explore the possibilities of entering the geostrophic regime of rotating convection with classical experimental tools: a table-top conventional convection cell with a height of 0.2 m and water as the working fluid. In order to examine our experimental measurements, we compare the spatial vorticity autocorrelations with the statistics from simulations of geostrophic convection reported earlier in [D. Nieves et al., “Statistical classification of flow morphology in rapidly rotating Rayleigh-Bénard convection,” Phys. Fluids 26, 086602 (2014)]. Our findings show that we have indeed access to the geostrophic convection regime and can observe the signatures of the typical flow features reported in the aforementioned simulations.

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“…An important effect of rotation is the development of columnar structures in the flow, with characteristic time-and length-scales depending on the rotation rate [5][6][7]. Depending on the type of turbulence, rotation can have additional effects, such as a transition to enhanced heat flux in rotating turbulent convection [8][9][10][11][12]. We therefore investigate two different turbulent flow configurations in this research: rotating (isothermal) turbulence driven by electromagnetic forcing and rotating turbulent Rayleigh-Bénard convection (RBC).…”

Section: Introductionmentioning

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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Optimal Prandtl number for heat transfer in rotating Rayleigh–Bénard convection

Cited by 62 publications

References 25 publications

Intensified heat transfer in modulated rotating Rayleigh–Bénard convection

Intensified heat transfer in modulated rotating Rayleigh–Bénard convection

Exploring the geostrophic regime of rapidly rotating convection with experiments

Geometry of tracer trajectories in rotating turbulent flows

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