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Hydromagnetic dynamo theory provides the prevailing theoretical description for the origin of magnetic fields in the universe. Here we consider the problem of kinematic, small-scale dynamo action driven by a random, incompressible,…

Plasma Physics · Physics 2011-03-10 Joanne Mason , Leonid Malyshkin , Stanislav Boldyrev , Fausto Cattaneo

While the saturated magnetic energy is independent of viscosity in dynamo experiments, it remains viscosity-dependent in state-of-the-art 3D direct numerical simulations (DNS). Extrapolating such viscous scaling-laws to realistic parameter…

Fluid Dynamics · Physics 2017-12-20 Kannabiran Seshasayanan , Basile Gallet , Alexandros Alexakis

Understanding the asymptotic behaviour of numerical dynamo models is critical for extrapolating results to the physical conditions that characterise terrestrial planetary cores. Here we investigate the behaviour of convection-driven dynamos…

Geophysics · Physics 2026-02-02 Justin A. Nicoski , Andy Esseln , Chris Davies , Michael A. Calkins

We study convection in a volumetrically heated fluid which is cooled from both plates and is under rotation through the use of direct numerical simulations. The onset of convection matches similar systems and predictions from asymptotic…

Fluid Dynamics · Physics 2025-03-27 Rodolfo Ostilla-Mónico , Ali Arslan

Combined action of helical motions of plasma (the $\alpha$ effect) and non-uniform (differential) rotation is a key dynamo mechanism of solar and galactic large-scale magnetic fields. Dynamics of magnetic helicity of small-scale fields is a…

Solar and Stellar Astrophysics · Physics 2022-09-20 N. Kleeorin , I. Rogachevskii

The effect of precession in a rotating sphere filled with fluid was studied with direct numerical simulations, both in the incompressible hydrodynamics (HD) and magnetohydrodynamics (MHD) scenarios. In both cases the asymptotic state and…

Fluid Dynamics · Physics 2022-12-13 Manuel I. Etchevest , Mauro Fontana , Pablo Dmitruk

In this study, we conducted a linear instability analysis of penetrative magneto-convection in rapidly rotating Boussinesq flows within tilted f-planes, under the influence of a uniform background magnetic field. We integrated wave theory…

Fluid Dynamics · Physics 2024-02-22 Fan Xu , Tao Cai

To study properties of magneto-hydrodynamic (MHD) convection and resultant dynamo activities in proto-neutron stars (PNSs), we construct a "PNS in a box" simulation model with solving compressible MHD equation coupled with a nuclear…

High Energy Astrophysical Phenomena · Physics 2022-02-21 Youhei Masada , Tomoya Takiwaki , Kei Kotake

The excitation and further sustenance of large-scale magnetic fields in rotating astrophysical systems, including planets, stars and galaxies, is generally thought to involve a fluid magnetic dynamo effect driven by helical…

Fluid Dynamics · Physics 2021-12-10 F. Rincon

We report the observation of dynamo action in the VKS experiment, i.e., the generation of magnetic field by a strongly turbulent swirling flow of liquid sodium. Both mean and fluctuating parts of the field are studied. The dynamo threshold…

Numerous studies have investigated the role of thermal instability in regulating the phase transition between the cold cloudy and warm diffuse medium of the interstellar medium. Considerable interest has also been devoted in investigating…

Astrophysics of Galaxies · Physics 2015-05-20 Maarit J. Mantere , Elizabeth Cole

This work concentrates on the effect of an irrotational forcing on a magnetized flow in the presence of rotation, baroclinicity, shear, or a combination of them. By including magnetic field in the model we can evaluate the occurrence of…

Astrophysics of Galaxies · Physics 2023-09-08 Albert Elias-López , Fabio Del Sordo , Daniele Viganò

Magnetic field observations of low-mass stars reveal an increase of magnetic activity with increasing rotation rate. The so-called activity-rotation relation is usually attributed to changes in the underlying dynamo processes generating the…

Solar and Stellar Astrophysics · Physics 2015-06-12 Martin Schrinner

In the present paper, we study a new type of large-scale instability, which arises in obliquely rotating electroconductive fluids with a small-scale external force of zero helicity. This force excites small-scale velocity oscillations with…

Plasma Physics · Physics 2017-11-27 M. I. Kopp , A. V. Tur , V. V. Yanovsky

The coexistence of motions on various scales is a remarkable feature of solar convection, which should be taken into account in analyses of the dynamics of magnetic fields. Therefore, it is important to investigate the factors responsible…

Solar and Stellar Astrophysics · Physics 2015-01-15 O. V. Shcheritsa , A. V. Getling , O. S. Mazhorova

Using a large number of numerical simulations we examine the steady state of rotating turbulent flows in triple periodic domains, varying the Rossby number $Ro$ (that measures the inverse rotation rate) and the Reynolds number $Re$ (that…

Fluid Dynamics · Physics 2018-03-14 Kannabiran Seshasayanan , Alexandros Alexakis

We investigate how rotating convection responds to the imposition of a latitudinally-varying heat flux at the base of the convective layer. This study is motivated by the solar near-surface shear layer, whose flows are thought to transition…

Solar and Stellar Astrophysics · Physics 2025-12-15 Kinfe Teweldebirhan , Rituparna Curt , Nicholas A. Featherstone

Using numerical MHD simulations, we have studied the evolution of the magnetorotational instability in stratified accretion disks in which the ionization fraction (and therefore resistivity) varies substantially with height. This model is…

Astrophysics · Physics 2009-11-07 Timothy Fleming , James M. Stone

Dynamo action refers to energy exchange processes through which magnetic fields are generated at the expense of kinetic energy of the plasma flows. Dynamos can generate magnetic fields across scales larger or smaller than the flows…

Convection is a fundamental physical process in the fluid cores of planets because it is the primary transport mechanism for heat and chemical species and the primary energy source for planetary magnetic fields. Key properties of…

Geophysics · Physics 2019-09-11 Céline Guervilly , Philippe Cardin , Nathanaël Schaeffer