Boundary zonal flows in rapidly rotating turbulent thermal convection

Abstract

Recently, in Zhang et al. (2020), it was found that in rapidly rotating turbulent Rayleigh-Bénard convection (RBC) in slender cylindrical containers (with diameter-to-height aspect ratio $\Gamma =1/2$) filled with a small-Prandtl-number fluid ($Pr\approx 0.8$), the Large Scale Circulation (LSC) is suppressed and a Boundary Zonal Flow (BZF) develops near the sidewall, characterized by a bimodal PDF of the temperature, cyclonic fluid motion, and anticyclonic drift of the flow pattern (with respect to the rotating frame). This BZF carries a disproportionate amount ($>60\%$) of the total heat transport for $Pr<1$ but decreases rather abruptly for larger $Pr$ to about $35\%$. In this work, we show that the BZF is robust and appears in rapidly rotating turbulent RBC in containers of different $\Gamma$ and in a broad range of $Pr$ and $Ra$. Direct numerical simulations for $0.1\le Pr\le 12.3$, $10^7\le Ra\le 5\times 10^9$, $10^5\le 1/Ek\le 10^7$ and $\Gamma$ = 1/3, 1/2, 3/4, 1 and 2 show that the BZF width ${\delta }_0$ scales with the Rayleigh number $Ra$ and Ekman number $Ek$ as ${\delta }_0/H\sim {\Gamma }^0{\mathrm{Pr}}^{\{-1/4,0\}}R{a}^{1/4}E{k}^{2/3}$ ($Pr<1,Pr>1$) and the drift frequency as $\omega /\Omega \sim {\Gamma }^{0}P{r}^{-4/3}RaE{k}^{5/3}$, where $H$ is the cell height and $\Omega$ the angular rotation rate. The mode number of the BZF is 1 for $\Gamma \lesssim 1$ and $2\Gamma$ for $\Gamma$ = {1,2} independent of $Ra$ and $Pr$. The BZF is quite reminiscent of wall mode states in rotating convection.

References in corpus (5)

• Approaching the Asymptotic Regime of Rapidly Rotating Convection: Boundary Layers vs Interior Dynamics
• Thermal Boundary Layer Equation for Turbulent Rayleigh-Benard Convection
• Boundary Zonal Flow in Rotating Turbulent Rayleigh-Bénard Convection
• Toroidal and poloidal energy in rotating Rayleigh-Bénard convection
• Turbulent rotating convection confined in a slender cylinder: the sidewall circulation

Cited by in corpus (10)

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• Robust wall modes and their interplay with bulk turbulence in confined rotating Rayleigh-Bénard convection
• Seven decades of exploring planetary interiors with rotating convection experiments
• Gravity drives the flow within the Stewartson layer in centrifugal convection
• Turbulent convection in rotating slender cells
• Rapidly Rotating Wall-Mode Convection
• Data-driven identification of the spatio-temporal structure of turbulent flows by streaming Dynamic Mode Decomposition
• Scale-by-scale kinetic energy flux calculations in simulations of rotating convection