Inverse cascade and symmetry breaking in rapidly rotating Boussinesq convection

Favier, Benjamin; Silvers, L. J.; Proctor, M. R. E.

doi:10.1063/1.4895131

Cited by 121 publications

(206 citation statements)

References 57 publications

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“…The final geostrophic turbulence regime is dominated by an inverse cascade that generates a depth invariant dipolar vortex which fills the horizontal extent of the computational domain [48]. An identical inverse cascade mechanism was identified previously in stochastically-forced, rotating homogeneous turbulence [52,53], and subsequent DNS studies have demonstrated it as a robust phenomenon in rapidly rotating convection [24,27,60].…”

Section: Introductionmentioning

confidence: 87%

Convection-driven kinematic dynamos at low Rossby and magnetic Prandtl numbers

et al. 2016

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Most large-scale planetary magnetic fields are thought to be driven by low Rossby number convection of a low magnetic Prandtl number fluid. Here kinematic dynamo action is investigated with an asymptotic, rapidly rotating dynamo model for the plane layer geometry that is intrinsically low magnetic Prandtl number. The thermal Prandtl number and Rayleigh number are varied to illustrate fundamental changes in flow regime, ranging from laminar cellular convection to geostrophic turbulence in which an inverse energy cascade is present. A decrease in the efficiency of the convection to generate a dynamo, as determined by an increase in the critical magnetic Reynolds number, is observed as the buoyancy forcing is increased. This decreased efficiency may result from both the loss of correlations associated with the increasingly disordered states of flow that are generated, and boundary layer behavior that enhances magnetic diffusion locally. We find that the spatial characteristics of α, and thus the large-scale magnetic field, is dependent only weakly on changes in flow behavior. In contrast to the large-scale magnetic field, the behavior of the small-scale magnetic field is directly dependent on, and therefore shows significant variations with, the small-scale convective flow field. However, our results are limited to the linear, kinematic dynamo regime; future simulations that include the Lorentz force are therefore necessary to assess the robustness of these results.

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Section: Introductionmentioning

confidence: 87%

Convection-driven kinematic dynamos at low Rossby and magnetic Prandtl numbers

et al. 2016

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“…Instead, we hypothesize that convection occurs in the form of 3-D geostrophic turbulence on smaller scales, whose energy then cascades upwards to larger-scale quasi-2-D flows (e.g. Mininni & Pouquet, 2010;Käpylä et al 2011;Chan & Mayr 2013;Favier et al 2014;Guervilly et al 2014;Rubio et al 2014;Stellmach et al 2014;Nataf & Schaeffer 2015), which are capable of efficiently generating observable magnetic fields. Ultimately, our findings suggest the need to revise current planetary dynamo models to include the effects of multiscale rotating convection dynamics and to determine how such flows produce planetary dynamo action.…”

Section: Discussionmentioning

confidence: 99%

Laboratory-numerical models of rapidly rotating convection in planetary cores

Cheng

Stellmach

Ribeiro

et al. 2015

Geophysical Journal International

116

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“…The effect is most clearly observed in the stress-free case (Fig 3). The formation of large scale vortices in rotating convection has recently been observed in simulations at larger E [21,22], where the large-scale energy accumulates predominantly in cyclonic structures. Such symmetry breaking is predicted to be absent in the asymptotic small Rossby number case [20].…”

Section: -2mentioning

confidence: 99%

Approaching the Asymptotic Regime of Rapidly Rotating Convection: Boundary Layers versus Interior Dynamics

et al. 2014

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Rapidly rotating Rayleigh-Bénard convection is studied by combining results from direct numerical simulations (DNS), laboratory experiments and asymptotic modeling. The asymptotic theory is shown to provide a good description of the bulk dynamics at low, but finite Rossby number. However, large deviations from the asymptotically predicted heat transfer scaling are found, with laboratory experiments and DNS consistently yielding much larger Nusselt numbers than expected. These deviations are traced down to dynamically active Ekman boundary layers, which are shown to play an integral part in controlling heat transfer even for Ekman numbers as small as 10 −7 . By adding an analytical parameterization of the Ekman transport to simulations using stress-free boundary conditions, we demonstrate that the heat transfer jumps from values broadly compatible with the asymptotic theory to states of strongly increased heat transfer, in good quantitative agreement with no-slip DNS and compatible with the experimental data. Finally, similarly to non-rotating convection, we find no single scaling behavior, but instead that multiple well-defined dynamical regimes exist in rapidly-rotating convection systems.

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Inverse cascade and symmetry breaking in rapidly rotating Boussinesq convection

Cited by 121 publications

References 57 publications

Convection-driven kinematic dynamos at low Rossby and magnetic Prandtl numbers

Convection-driven kinematic dynamos at low Rossby and magnetic Prandtl numbers

Laboratory-numerical models of rapidly rotating convection in planetary cores

Approaching the Asymptotic Regime of Rapidly Rotating Convection: Boundary Layers versus Interior Dynamics

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