Coriolis effect on centrifugal buoyancy-driven convection in a thin cylindrical shell
AuthorRouhi, A; Lohse, D; Marusic, I; Sun, C; Chung, D
Source TitleJournal of Fluid Mechanics
PublisherCambridge University Press (CUP)
Document TypeJournal Article
CitationsRouhi, A., Lohse, D., Marusic, I., Sun, C. & Chung, D. (2021). Coriolis effect on centrifugal buoyancy-driven convection in a thin cylindrical shell. Journal of Fluid Mechanics, 910, https://doi.org/10.1017/jfm.2020.959.
Access StatusOpen Access
Open Access URLPublished version
We study the effect of the Coriolis force on centrifugal buoyancy-driven convection in a rotating cylindrical shell with inner cold wall and outer hot wall. This is done by performing direct numerical simulations for increasing inverse Rossby number Ro−1 from zero (no Coriolis force) to 20 (very large Coriolis force) and for Rayleigh number Ra from 107 to 1010 and Prandtl number Pr=0.7, corresponding to air. We invoke the thin-shell limit, which neglects the curvature and radial variations of the centripetal acceleration. As Ro−1 increases from zero, the system forms an azimuthal bidirectional wind that reaches its maximum momentum at an optimal Ro−1opt, associated with a maximal skin-friction coefficient Cf and a minimal Nusselt number Nu. Just beyond Ro−1opt, the wind weakens and an axial, quasi-two-dimensional cyclone, corotating with the system, begins to form. A local ‘turbulence’ inverse Rossby number (non-dimensionalised by the eddy turnover time) determines the onset of cyclone formation for all Ra, when its value reaches approximately 4. At Ro−1≫Ro−1opt, the system falls into the geostrophic regime with a sudden drop in Nu. The bidirectional wind for Ro−1≤Ro−1opt is a feature of this system, as it hastens the boundary layer transition from laminar to turbulent, towards the ultimate regime. We see the onset of this transition at Ra=1010 and Ro−1≃Ro−1opt, although the mean flow profile has not yet fully collapsed on the Prandtl–von Kármán (logarithmic) law.
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