Double diffusive convection in the finger regime for different Prandtl and Schmidt numbers

Yang, Yantao

doi:10.1007/s10409-020-00973-0

Cited by 10 publications

(4 citation statements)

References 27 publications

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“…Briefly, the large-scale flow can take different sizes/numbers of rolls, which give rise to different transport properties for an identical set of control parameters and the same boundary conditions of the system [ 87–89 ]. Similar phenomena have also been found in other model systems for turbulent flows such as Taylor–Couette turbulence [ 90 ], double-diffusive convection [ 91 , 92 ], von Karman flow [ 93 ] and Couette flow with span-wise rotation [ 94 ]. In some model studies of continent-mantle coupling of the Earth, it has been found that changing the thermal boundary conditions can lead to different organizations of large-scale coherent structures [ 95–97 ].…”

Section: Discussionsupporting

confidence: 80%

Tuning heat transport via coherent structure manipulation: recent advances in thermal turbulence

Xia

Huang

Xie

et al. 2023

National Science Review

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Tuning transport properties through the manipulation of elementary structures has received a great success in many areas, such as condensed matter physics. However, the ability to manipulate coherent structures in turbulent flows is much less explored. This article reviews a recently discovered mechanism of tuning turbulent heat transport via coherent structure manipulation. We first show how this mechanism can be realized by applying simple geometrical confinement to a classical thermally-driven turbulence, which leads to the condensation of elementary coherent structures and significant heat-transport enhancement, despite the resultant slower flow. Some potential applications of this new paradigm in passive heat management are also discussed. We then explain how the heat transport behaviors in seemingly different turbulence systems can be understood by this unified framework of coherent structure manipulation. Several future directions in this research area are also outlined.

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Section: Discussionsupporting

confidence: 80%

Tuning heat transport via coherent structure manipulation: recent advances in thermal turbulence

Xia

Huang

Xie

et al. 2023

National Science Review

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“…Staircases were found by Stellmach et al. (2011) in a triply periodic domain, and more recently by Yang (2020) in a bounded Cartesian configuration, upon reaching , slightly above the maximum value considered in this work (). Future work should seek confirmation of spontaneous layer formation in a spherical shell.…”

Section: Discussionsupporting

confidence: 53%

“…2020) consists in introducing an effective density ratio within the bulk of the domain expressed by This measure is appropriate to fingering convection in Cartesian domains with , given the piecewise-linear nature of the composition profile (see e.g. figure 2 of Yang 2020). This estimate is, however, not suitable close to onset as the boundary layer definition becomes ill posed.…”

Section: Fingering Convectionmentioning

confidence: 99%

Fingering convection in a spherical shell

Tassin,

Gastine,

Fournier

2024

J. Fluid Mech.

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We use $123$ three-dimensional direct numerical simulations to study fingering convection in non-rotating spherical shells. We investigate the scaling behaviour of the flow length scale, the non-dimensional heat and compositional fluxes $Nu$ and $Sh$ and the mean convective velocity over the fingering convection instability domain defined by $1 \leq R_\rho < Le$ , $R_\rho$ being the ratio of density perturbations of thermal and compositional origins and $Le$ the Lewis number. We show that the chemical boundary layers are marginally unstable and adhere to the laminar Prandtl–Blasius model, hence explaining the asymmetry between the inner and outer spherical shell boundary layers. We develop scaling laws for two asymptotic regimes close to the two edges of the instability domain, namely $R_\rho \lesssim Le$ and $R_\rho \gtrsim 1$ . For the former, we develop novel power laws of a small parameter $\epsilon$ measuring the distance to onset, which differ from theoretical laws published to date in Cartesian geometry. For the latter, we find that the Sherwood number $Sh$ gradually approaches a scaling $Sh\sim Ra_\xi ^{1/3}$ when $Ra_\xi \gg 1$ ; and that the Péclet number accordingly follows $Pe \sim Ra_\xi ^{2/3} |Ra_T|^{-1/4}$ , $Ra_T$ and $Ra_{\xi}$ being the thermal and chemical Rayleigh numbers. When the Reynolds number exceeds a few tens, we report on a secondary instability which takes the form of large-scale toroidal jets which span the entire spherical domain. Jets distort the fingers, resulting in Reynolds stress correlations, which in turn feed the jet growth until saturation. This nonlinear phenomenon can yield relaxation oscillation cycles.

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“…Often the goal is to enhance the heat transfer. This can be done using a variety of strategies such as adding bubbles [6][7][8][9] or multicomponent fluids with phase change [10][11][12][13][14], adding roughness [15][16][17][18][19], vibration [20,21], changing the velocity boundary conditions [22], and coherent structure manipulation by an additional stabilization due to confinement, rotation, double-diffusive effect or an external magnetic field [23][24][25][26][27][28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Heat transfer enhancement in Rayleigh-Bénard convection using a single passive barrier

Liu

Huisman

2020

Phys. Rev. Fluids

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In this numerical study on Rayleigh-Bénard convection, we seek to improve the heat transfer by passive means. To this end we introduce a single tilted conductive barrier centered in an aspect ratio one cell, breaking the symmetry of the geometry and to channel the ascending hot and descending cold plumes. We study the global and local heat transfer and the flow organization for Rayleigh numbers 10 5 Ra 10 9 for a fixed Prandtl number of Pr = 4.3. We find that the global heat transfer can be enhanced up to 18%, and locally around 800%. The averaged Reynolds number is always decreased when a barrier is introduced, even for those cases where the global heat transfer is increased. We map the entire parameter space spanned by the orientation and the size of a single barrier for Ra = 10 8 .

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Double diffusive convection in the finger regime for different Prandtl and Schmidt numbers

Cited by 10 publications

References 27 publications

Tuning heat transport via coherent structure manipulation: recent advances in thermal turbulence

Tuning heat transport via coherent structure manipulation: recent advances in thermal turbulence

Fingering convection in a spherical shell

Heat transfer enhancement in Rayleigh-Bénard convection using a single passive barrier

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