Statistics of temperature and velocity fluctuations in supergravitational convective turbulence

Wang, Dongpu; Liu, Jing; Zhou, Quan; Sun, Chao

doi:10.1007/s10409-022-22387-x

Cited by 8 publications

(4 citation statements)

References 35 publications

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“…2021; Wang et al. 2023) and spherical (Gastine, Wicht & Aurnou 2015) RB cells also attract a lot of interest. The uniform gravity is substituted by the centrifugal force or gravity that varies in the direction of the temperature gradient.…”

Section: Introductionmentioning

confidence: 99%

“…Some manifold and involute flow structures are formed in the cell (Niemela et al 2001;Xi, Lam & Xia 2004;Sun, Xia & Tong 2005;Wang et al 2021). Moreover, apart from the classical RB model with rectangular cells, annular (Pitz, Marxen & Chew 2017;Kang et al 2019;Jiang et al 2020;Rouhi et al 2021;Wang et al 2023) and spherical (Gastine, Wicht & Aurnou 2015) RB cells also attract a lot of interest. The uniform gravity is substituted by the centrifugal force or gravity that varies in the direction of the temperature gradient.…”

Section: Introductionmentioning

confidence: 99%

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From sheared annular centrifugal Rayleigh–Bénard convection to radially heated Taylor–Couette flow: exploring the impact of buoyancy and shear on heat transfer and flow structure

Zhong,

Wang,

Sun

2023

J. Fluid Mech.

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We investigate the coupling effect of buoyancy and shear based on an annular centrifugal Rayleigh–Bénard convection (ACRBC) system in which two cylinders rotate with an angular velocity difference. Direct numerical simulations are performed in a Rayleigh number range $10^6\leq Ra\leq 10^8$ , at fixed Prandtl number $Pr=4.3$ , inverse Rossby number $Ro^{-1}=20$ , and radius ratio $\eta =0.5$ . The shear, represented by the non-dimensional rotational speed difference $\varOmega$ , varies from $0$ to $10$ , corresponding to an ACRBC without shear and a radially heated Taylor–Couette flow with only the inner cylinder rotating, respectively. A stable regime is found in the middle part of the interval for $\varOmega$ , and divides the whole parameter space into three regimes: buoyancy-dominated, stable and shear-dominated. Clear boundaries between the regimes are given by linear stability analysis, meaning the marginal state of the flow. In the buoyancy-dominated regime, the flow is a quasi-two-dimensional flow on the $r\varphi$ plane; as shear increases, both the growth rate of instability and the heat transfer are depressed. In the shear-dominated regime, the flow is mainly on the $rz$ plane. The shear is so strong that the temperature acts as a passive scalar, and the heat transfer is greatly enhanced. The study shows that shear can stabilize buoyancy-driven convection, makes a detailed analysis of the flow characteristics in different regimes, and reveals the complex coupling mechanism of shear and buoyancy, which may have implications for fundamental studies and industrial designs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

From sheared annular centrifugal Rayleigh–Bénard convection to radially heated Taylor–Couette flow: exploring the impact of buoyancy and shear on heat transfer and flow structure

Zhong,

Wang,

Sun

2023

J. Fluid Mech.

Self Cite

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“…Moreover, in order to reach the geostrophic regime, many experiments are chasing for even smaller Ek and higher Ra. One can enhance Ra by using the so-called annular centrifugal Rayleigh-Bénard convection (ACRBC) system through the generation of supergravity induced by rapid rotation and the strong centrifugal force (Jiang et al 2020;Wang et al 2022), or simply by increasing the system height H. However, for the ACRBC system, the rotating axis is perpendicular to the effective gravity (centrifugal force), which is different from the rotating RBC system (rotating axis is parallel to the gravity). Thus, increasing H is a more reasonable method to increase Ra in a rotating RBC system.…”

Section: Introductionmentioning

confidence: 99%

“…2020; Wang et al. 2022), or simply by increasing the system height . However, for the ACRBC system, the rotating axis is perpendicular to the effective gravity (centrifugal force), which is different from the rotating RBC system (rotating axis is parallel to the gravity).…”

Section: Introductionmentioning

confidence: 99%

Heat transport and flow morphology of geostrophic rotating Rayleigh–Bénard convection in the presence of boundary flow

Ding,

Xia

2023

J. Fluid Mech.

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Using direct numerical simulations, we investigate the heat transport in bulk and boundary flows separately in rotating Rayleigh–Bénard convection in cylindrical cells. In the bulk we observe a steep scaling relationship between the Nusselt number ( $Nu$ ) and the Rayleigh number ( $Ra$ ), which is consistent with the results from simulations using periodic boundary conditions. For the boundary flow, we observe a power law $Nu_{BF}\sim (Ra/Ra_w)^1$ at the leading order, where $Nu_{BF}$ is the local Nusselt number of the boundary flow and $Ra_w$ is the onset Rayleigh number of the wall mode. We develop a model using the boundary layer marginal stability theory to explain this power law, and further show that a more precise description of the data can be obtained if a higher-order correction is introduced. A striking finding of our study is the observation of a sharp transition in flow state, manifested by a sudden drop in $Nu_{BF}$ with a corresponding collapse of the boundary flow coherency. After the transition, the boundary flow breaks into vortices, leading to a reduction in flow coherency and heat transport efficiency. As the physical properties of the vortices should not depend on the aspect ratio, $Nu_{BF}$ for all aspect ratios collapse together after the transition. Moreover, the centrifugal force helps trigger the breakdown of the coherent boundary flow state. For this reason, $Nu_{BF}$ for the cases with non-zero centrifugal force collapse together. We further develop a method that enables us to separate the contributions from the bulk and boundary flows in the global Nusselt number using only the global $Nu$ and it does not require the centrifugal force to be absent.

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Temperature fluctuations and heat transport in partitioned supergravitational thermal turbulence

Wang,

Liu,

Lai

et al. 2024

Acta Mech. Sin.

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Statistics of temperature and velocity fluctuations in supergravitational convective turbulence

Cited by 8 publications

References 35 publications

From sheared annular centrifugal Rayleigh–Bénard convection to radially heated Taylor–Couette flow: exploring the impact of buoyancy and shear on heat transfer and flow structure

From sheared annular centrifugal Rayleigh–Bénard convection to radially heated Taylor–Couette flow: exploring the impact of buoyancy and shear on heat transfer and flow structure

Heat transport and flow morphology of geostrophic rotating Rayleigh–Bénard convection in the presence of boundary flow

Temperature fluctuations and heat transport in partitioned supergravitational thermal turbulence

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