Related papers: Approaching a realistic force balance in geodynamo…
Rapidly rotating convection-driven dynamos are investigated under different kinematic and magnetic boundary conditions using DNS. At a fixed rotation rate, represented by the Ekman number $E=5\times10^{-7}$, the thermal forcing is varied…
A dynamo model is presented, based on a previously introduced kinematic model, in which the reaction of the magnetic field on the mass flow through the Lorentz force is included. Given the base mass flow corresponding to the case with no…
Magnetorotational turbulence draws its energy from gravity and ultimately releases it via dissipation. However, the quantitative details of this energy flow have not been assessed for global disk models. In this work we examine the…
In many astrophysical environments, self-gravity can generate kinetic energy, which, in principle, is available for driving dynamo action. Using direct numerical simulations, we show that in unstirred self-gravitating subsonic turbulence…
Natural dynamos such as planets and stars generate global scale magnetic field despite the inferred presence of small scale turbulence. Such systems are known as large scale dynamos and are typically driven by convection and influenced by…
Context: The solar rotation profile is conical rather than cylindrical as one could expect from classical rotating fluid dynamics (e.g. Taylor-Proudman theorem). Thermal coupling to the tachocline, baroclinic effects and latitudinal…
This paper considers the dominant dynamical, thermal and rotational balances within the solar convection zone. The reasoning is such that: Coriolis forces balance pressure gradients. Background vortex stretching, baroclinic torques and…
Planets and stars are able to generate coherent large-scale magnetic fields by helical convective motions in their interiors. This process, known as hydromagnetic dynamo, involves nonlinear interaction between the flow and magnetic field.…
In the outer envelope of the Sun and in other stars, differential rotation and meridional circulation are maintained via the redistribution of momentum and energy by convective motions. In order to properly capture such processes in a…
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,…
Precession of planets or moons affects internal liquid layers by driving flows, instabilities and possibly dynamos.The energy dissipated by these phenomena can influence orbital parameters such as the planet's spin rate.However, there is no…
Magneto-convection simulations with two scenarios have been performed: In one, horizontal magnetic field is advected into the computational domain by fluid entering at the bottom. In the other, an initially uniform vertical magnetic field…
We show that a simple, modified version of the Magnetorotational Instability (MRI) can develop in the outer liquid core of the Earth, in the presence of a background shear. It requires either thermal wind, or a primary instability, such as…
The planet Mercury possesses a small but highly dynamic magnetosphere in which the role and dynamics of electrons are still largely unknown. We aim at modeling the global dynamics of solar wind electrons impinging on Mercury's…
Recent analysis of the helioseismic observations indicate that the previously observed surface torsional oscillations extend significantly downwards into the solar convection zone. In an attempt to understand these oscillations, we study…
We present analytical examples of fluid dynamos that saturate through the action of the Coriolis and inertial terms of the Navier-Stokes equation. The flow is driven by a body force and is subject to global rotation and uniform sweeping…
Rotating Rayleigh--B\'enard convection is an oft-employed model system to evaluate the interplay of buoyant forcing and Coriolis forces due to rotation, an eminently relevant interaction of dynamical effects found in many geophysical and…
We present the first results from three-dimensional spherical shell simulations of magnetic dynamo action realized by turbulent convection penetrating downward into a tachocline of rotational shear. This permits us to assess several…
We present a local but fully nonlinear model of the solar tachocline, using three-dimensional direct numerical simulations. The tachocline forms naturally as a statistically steady balance between Coriolis, pressure, buoyancy and Lorentz…
Magnetic helicity is robustly conserved in systems with very large magnetic Reynolds numbers, including most systems of astrophysical interest, and unlike kinetic and magnetic energy is not dissipated at small scales. This plays a major…