Precession-driven dynamos in a full sphere and the role of large scale cyclonic vortices

Abstract

Precession has been proposed as an alternative power source for planetary dynamos. Previous hydrodynamic simulations suggested that precession can generate very complex flows in planetary liquid cores [Y. Lin, P. Marti, and J. Noir, "Shear-driven parametric instability in a precessing sphere," Physics of Fluids 27, 046601 (2015)]. In the present study, we numerically investigate the magnetohydrodynamics of a precessing sphere. We demonstrate precession driven dynamos in different flow regimes, from laminar to turbulent flows. In particular, we highlight the magnetic field generation by large scale cyclonic vortices, which has not been explored previously. In this regime, dynamos can be sustained at relatively low Ekman numbers and magnetic Prandtl numbers, which paves the way for planetary applications.

22 pages, 12 figures

References in corpus (3)

• Shear-driven parametric instability in a precessing sphere
• Precession-driven dynamos in a full sphere and the role of large scale cyclonic vortices
• Generation of magnetic fields by large-scale vortices in rotating convection

Cited by in corpus (14)

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• Precession-driven dynamos in a full sphere and the role of large scale cyclonic vortices
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• Turbulent kinematic dynamos in ellipsoids driven by mechanical forcing
• A past lunar dynamo thermally driven by the precession of its inner core
• Kinematic dynamo action of a precession driven flow based on the results of water experiments and hydrodynamic simulations
• Interplay between geostrophic vortices and inertial waves in precession-driven turbulence
• Rotational dynamics of planetary cores: instabilities driven by precession, libration and tides
• Magnetic quenching of the inverse cascade in rapidly rotating convective turbulence
• The global flow state in a precessing cylinder
• Kinematic dynamos in triaxial ellipsoids
• Dynamo induced by time-periodic force
• Behavior of hydrodynamic and magnetohydrodynamic turbulence in a rotating sphere with precession and dynamo action