Laboratory Models of Planetary Core-Style Convective Turbulence

Hawkins, Emily; Cheng, Jonathan; Abbate, Jewel A.; Pilegard, Timothy; Stellmach, Stephan; Julien, Keith; Aurnou, J. M.

doi:10.3390/fluids8040106

Cited by 9 publications

(8 citation statements)

References 168 publications

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“…This is in line with the analysis of Hawkins et al. (2023) (also covered in Hawkins 2020), who similarly reported co-scaling of VAC and CIA relations based on measurements using laser Doppler velocimetry. We can insert these numbers into the scaling relations (2.11) and (2.14) for a quantitative comparison.…”

Section: Reynolds Number Resultssupporting

confidence: 90%

“…Hawkins et al. (2023) conclude that pure CIA scaling is not observed given that the is still affected by boundary-layer dynamics and thus not diffusion-free yet – a result that we share (Cheng et al. 2020).…”

Section: Reynolds Number Resultssupporting

confidence: 66%

“…The experimental results by Hawkins et al. (2023) cover a significant range and ; they are the reported RRBC Reynolds number data closest to the current study in terms of and , and are included with dots. Numerical and experimental results corresponding to a smaller cylindrical convection cell at and taken from Kunnen, Geurts & Clercx (2010) and Rajaei et al.…”

Section: Reynolds Number Resultsmentioning

confidence: 73%

“…Small filled circles: experiments of Hawkins et al. (2023). Up triangles: DNS in a cylinder (Kunnen et al.…”

Section: Reynolds Number Resultsmentioning

confidence: 99%

“…2021; Hawkins et al. 2023), direct numerical simulations (DNS) on fine meshes (e.g. Stellmach et al.…”

Section: Introductionmentioning

confidence: 99%

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Reynolds number scaling and energy spectra in geostrophic convection

et al. 2023

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We report flow measurements in rotating Rayleigh–Bénard convection in the rotationally constrained geostrophic regime. We apply stereoscopic particle image velocimetry to measure the three components of velocity in a horizontal cross-section of a water-filled cylindrical convection vessel. At a constant, small Ekman number $Ek=5\times 10^{-8}$ , we vary the Rayleigh number $Ra$ between $10^{11}$ and $4\times 10^{12}$ to cover various subregimes observed in geostrophic convection. We also include one non-rotating experiment. The scaling of the velocity fluctuations (expressed as the Reynolds number $Re$ ) is compared to theoretical relations expressing balances of viscous–Archimedean–Coriolis (VAC) and Coriolis–inertial–Archimedean (CIA) forces. Based on our results we cannot decide which balance is most applicable here; both scaling relations match equally well. A comparison of the current data with several other literature datasets indicates a convergence towards diffusion-free scaling of velocity as $Ek$ decreases. However, at lower $Ra$ , the use of confined domains leads to prominent convection in the wall mode near the sidewall. Kinetic energy spectra point at an overall flow organisation into a quadrupolar vortex filling the cross-section. This quadrupolar vortex is a quasi-two-dimensional feature; it manifests only in energy spectra based on the horizontal velocity components. At larger $Ra$ , the spectra reveal the development of a scaling range with exponent close to $-5/3$ , the classical exponent for inertial range scaling in three-dimensional turbulence. The steeper $Re(Ra)$ scaling at low $Ek$ and development of a scaling range in the energy spectra are distinct indicators that a fully developed, diffusion-free turbulent bulk flow state is approached, sketching clear perspectives for further investigation.

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Section: Reynolds Number Resultssupporting

confidence: 90%

Section: Reynolds Number Resultssupporting

confidence: 66%

Section: Reynolds Number Resultsmentioning

confidence: 73%

“…Small filled circles: experiments of Hawkins et al. (2023). Up triangles: DNS in a cylinder (Kunnen et al.…”

Section: Reynolds Number Resultsmentioning

confidence: 99%

“…2021; Hawkins et al. 2023), direct numerical simulations (DNS) on fine meshes (e.g. Stellmach et al.…”

Section: Introductionmentioning

confidence: 99%

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Reynolds number scaling and energy spectra in geostrophic convection

et al. 2023

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Direct numerical simulations of the transition between rotation- to buoyancy-dominated regimes in rotating Rayleigh–Bénard convection

Song,

Kannan,

Shishkina

et al. 2024

International Journal of Heat and Mass Transfer

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Regimes in rotating Rayleigh–Bénard convection over rough boundaries

Tripathi,

Joshi

2024

J. Fluid Mech.

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The present work focuses on the effect of rough horizontal boundaries on the heat transfer in rotating Rayleigh–Bénard convection. We measure the non-dimensional heat transfer, the Nusselt number $Nu$ , for various strengths of the buoyancy forcing characterized by the Rayleigh number $Ra$ ( ${10^5}\mathrm{\ \mathbin{\lower.3ex\hbox{$\buildrel< \over {\smash{\scriptstyle\sim}\vphantom{_x}}$}}\ }Ra\mathrm{\ \mathbin{\lower.3ex\hbox{$\buildrel< \over {\smash{\scriptstyle\sim}\vphantom{_x}}$}}\ }5 \times {10^8}$ ), and rotation rates characterized by the Ekman number E ( $1.4 \times {10^{ - 5}}\mathrm{\ \mathbin{\lower.3ex\hbox{$\buildrel< \over {\smash{\scriptstyle\sim}\vphantom{_x}}$}}\ }E\mathrm{\ \mathbin{\lower.3ex\hbox{$\buildrel< \over {\smash{\scriptstyle\sim}\vphantom{_x}}$}}\ }7.6 \times {10^{ - 4}}$ ) for aspect ratios $\varGamma \approx 1$ , $2.8$ and $6.7$ . Similar to rotating convection with smooth horizontal boundaries, the so-called rotationally constrained (RC), rotation-affected (RA) and rotation-unaffected (RuA) regimes of heat transfer seem to persist for rough horizontal boundaries. However, the transition from the RC regime to RA regime occurs at a lower Rayleigh number for rough boundaries. For all experiments with rough boundaries in this study, the thermal and Ekman boundary layers are in a perturbed state, leading to a significant enhancement in the heat transfer as compared with that for smooth walls. However, the enhancement in heat transfer due to wall roughness is observed to attain a maximum in the RC regime. We perform companion direct numerical simulations of rotating convection over smooth walls to suggest a phenomenology explaining this observation. We propose that the heat transfer enhancement due to wall roughness reaches a maximum when the strength and coherence of the columnar structures are both significant, which enables efficient vertical transport of the additional thermal anomalies generated by the roughness at the top and bottom walls.

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Laboratory Models of Planetary Core-Style Convective Turbulence

Cited by 9 publications

References 168 publications

Reynolds number scaling and energy spectra in geostrophic convection

Reynolds number scaling and energy spectra in geostrophic convection

Direct numerical simulations of the transition between rotation- to buoyancy-dominated regimes in rotating Rayleigh–Bénard convection

Regimes in rotating Rayleigh–Bénard convection over rough boundaries

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