Open Access
Boundary Layer Control of Rotating Convection Systems
Eric M. King,Stephan Stellmach,Jerome Noir,Ulrich Hansen,Jonathan M. Aurnou +4 more
- Vol. 2008
TLDR
This work forms a predictive description of the transition between the two regimes on the basis of the competition between these two boundary layers, and unifies the disparate results of an extensive array of previous experiments, and is broadly applicable to natural convection systems.Abstract:
Turbulent rotating convection is an important dynamical process occurring on nearly all planetary and stellar bodies, influencing many observed features such as magnetic fields, atmospheric jets and emitted heat flux patterns. For decades, it has been thought that the importance of rotation's influence on convection depends on the competition between the two relevant forces in the system: buoyancy (non-rotating) and Coriolis (rotating). The force balance argument does not, however, accurately predict the transition from rotationally controlled to non-rotating heat transfer behaviour. New results from laboratory and numerical experiments suggest that the transition is in fact controlled by the relative thicknesses of the thermal (non-rotating) and Ekman (rotating) boundary layers. Turbulent rotating convection controls many observed features in stars and planets, such as magnetic fields. It has been argued that the influence of rotation on turbulent convection dynamics is governed by the ratio of the relevant global-scale forces: the Coriolis force and the buoyancy force. This paper presents results from laboratory and numerical experiments which exhibit transitions between rotationally dominated and non-rotating behaviour that are not determined by this global force balance. Instead, the transition is controlled by the relative thicknesses of the thermal (non-rotating) and Ekman (rotating) boundary layers. Turbulent rotating convection controls many observed features of stars and planets, such as magnetic fields, atmospheric jets and emitted heat flux patterns1,2,3,4,5,6. It has long been argued that the influence of rotation on turbulent convection dynamics is governed by the ratio of the relevant global-scale forces: the Coriolis force and the buoyancy force7,8,9,10,11,12. Here, however, we present results from laboratory and numerical experiments which exhibit transitions between rotationally dominated and non-rotating behaviour that are not determined by this global force balance. Instead, the transition is controlled by the relative thicknesses of the thermal (non-rotating) and Ekman (rotating) boundary layers. We formulate a predictive description of the transition between the two regimes on the basis of the competition between these two boundary layers. This transition scaling theory unifies the disparate results of an extensive array of previous experiments8,9,10,11,12,13,14,15, and is broadly applicable to natural convection systems.read more
Citations
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Journal ArticleDOI
Dynamo Scaling Laws and Applications to the Planets
TL;DR: The scaling laws for planetary dynamos relate the characteristic magnetic field strength, characteristic flow velocity and other properties to primary quantities such as core size, rotation rate, electrical conductivity and heat flux as discussed by the authors.
Journal ArticleDOI
On the genesis of the Earth's magnetism
Paul H. Roberts,Eric M. King +1 more
TL;DR: The geophysical relevance of the experiments and simulations is called into question: the dynamics of Earth's core are too complex, and operate across time and length scales too broad to be captured by any single laboratory experiment, or resolved on present-day computers.
Journal ArticleDOI
Statistical and physical balances in low Rossby number Rayleigh–Bénard convection
TL;DR: In this paper, the authors studied rapid rotating Rayleigh-benard convection using an asymptotically reduced equation set valid in the limit of low Rossby numbers and identified four distinct dynamical regimes: a disordered cellular regime near threshold, a regime of weakly interacting convective Taylor columns at larger Rayleigh numbers, followed by a breakdown of the convective columns into disordered plume regime characterized by reduced efficiency and finally by geostrophic turbulence.
Journal ArticleDOI
Heat transfer by rapidly rotating Rayleigh–Bénard convection
TL;DR: In this paper, an exact scaling law for heat transfer by geostrophic convection, by considering the stability of the thermal boundary layers, where, and are the Nusselt, Rayleigh and Ekman numbers, respectively, and is the critical Rayleigh number for the onset of convection.
Journal ArticleDOI
Rotating convective turbulence in Earth and planetary cores
Jonathan M. Aurnou,Michael A. Calkins,Jonathan S. Cheng,Keith Julien,E.M. King,David Nieves,Krista M. Soderlund,Stephan Stellmach +7 more
TL;DR: In this paper, a closely coupled suite of advanced asymptotically-reduced theoretical models, efficient Cartesian direct numerical simulations (DNS) and laboratory experiments are presented.
References
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Journal ArticleDOI
The viscous boundary layer at the free surface of a rotating baroclinic fluid
TL;DR: The properties of the viscous boundary layer at the free surface of a rotating baroclinic fluid are analyzed and compared with those of the well-known Ekman boundary layer.
Dissertation
L'instabilité elliptique dans les enveloppes fluides des planètes et des étoiles
TL;DR: In this paper, the authors present a series of simulations of l'instabilite elliptique in geometrie ellipsoidale, which nous permettent d'obtenir des lois d'echelles the caracterisant.
Journal ArticleDOI
Convection with misaligned gravity and rotation: simulations and rotating mixing length theory
TL;DR: In this article, the authors investigated the effects of rotation on the bulk properties of convection at different latitudes, focusing on determining the relation between the heat flux and temperature gradient.
Journal ArticleDOI
Mixing and dissipation in a geostrophic buoyancy-driven circulation
TL;DR: In this article, the authors used numerical simulations of a geostrophic circulation, resolving turbulence and convection, to examine the rates of dissipation and mixing and found that the total rate of mixing accounts for over 95% of the mechanical energy supply.
Journal ArticleDOI
Scaling of heat transport near onset in rapidly rotating convection
TL;DR: In this article, the scaling of heat transport in the geostrophic regime of rotating Rayleigh-Benard convection near onset for small Ekman number Ek from the perspective of weakly nonlinear theory was considered.