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Numerical simulations of dynamos in rotating Rayleigh-B\'enard convection in plane layers are presented. Two different types of dynamos exist which obey different scaling laws for the amplitude of the magnetic field. The transition between…

Fluid Dynamics · Physics 2015-06-12 A. Tilgner

The rapid rotation of planets causes cyclonic thermal turbulence in their cores which may generate the large-scale magnetic fields observed outside the planets. We consider the model which enables us reproduce the typical features of…

Fluid Dynamics · Physics 2020-01-29 M. Reshetnyak , P. Hejda

The calling card of solar magnetism is the sunspot cycle, during which sunspots regularly reverse their polarity sense every 11 years. However, a number of more complicated time-dependent behaviors have also been identified. In particular,…

Solar and Stellar Astrophysics · Physics 2020-04-06 Loren Matilsky , Juri Toomre

The non-collisional interaction between conducting obstacles and magnetized plasma winds can be found in different scenarios, from the interaction occurring between regions inside galaxy clusters to the interaction between the solar wind…

Earth and Planetary Astrophysics · Physics 2015-06-22 Norberto Romanelli , Daniel Gomez , Cesar Bertucci , Magda Delva

The electroweak phase transition, if proceeding through nucleation and growth of bubbles, should generate large scale turbulent flow, which in turn generates magnetic turbulence and hence magnetic fields on the scale of turbulent flow. We…

High Energy Physics - Phenomenology · Physics 2009-10-28 Gordon Baym , Dietrich Bödeker , Larry McLerran

The generation of magnetic field in an electrically conducting fluid generally involves the complicated nonlinear interaction of flow turbulence, rotation and field. This dynamo process is of great importance in geophysics, planetary…

Fluid Dynamics · Physics 2021-10-04 Steven Tobias

Solar magnetic fields comprise an 11-year activity cycle, represented by the number of sunspots. The maintenance of such a solar magnetic field can be attributed to fluid motion in the convection zone, i.e. a dynamo. This study conducts the…

Solar and Stellar Astrophysics · Physics 2022-08-24 Ryota Shimada , Hideyuki Hotta , Takaaki Yokoyama

The emergence of a large scale magnetic field from randomly forced isotropic strongly helical flows is discussed in terms of the inverse cascade of magnetic helicity and the alpha-effect. In simulations of such flows the maximum field…

Astrophysics · Physics 2007-05-23 Axel Brandenburg

In a recent paper (Phys. Rev. Lett. 94 (2005), 184506; physics/0411050) it was shown that a simple mean-field dynamo model with a spherically symmetric helical turbulence parameter alpha can exhibit a number of features which are typical…

Geophysics · Physics 2007-05-23 Frank Stefani , Gunter Gerbeth , Uwe Guenther , Mingtian Xu

Kinematic dynamo theory is presented here for turbulent conductive fluids. We describe how inhomogeneous magnetic fluctuations are generated below the viscous scale of turbulence where the spatial smoothness of the velocity permits a…

chao-dyn · Physics 2009-10-31 M. Chertkov , G. Falkovich , I. Kolokolov , M. Vergassola

The dipole-multipole transition in rapidly rotating dynamos is investigated through the analysis of forced magnetohydrodynamic waves in an unstably stratified fluid. The focus of this study is on the inertia-free limit applicable to…

Fluid Dynamics · Physics 2023-09-25 Debarshi Majumder , Binod Sreenivasan , Gaurav Maurya

Magnetic fields are ubiquitous in the Universe. Extragalactic disks, halos and clusters have consistently been shown, via diffuse radio-synchrotron emission and Faraday rotation measurements, to exhibit magnetic field strengths ranging from…

The contribution of small scale turbulent fluctuations to the induction of mean magnetic field is investigated in our liquid sodium spherical Couette experiment with an imposed magnetic field.An inversion technique is applied to a large…

Fluid Dynamics · Physics 2015-10-06 Simon Cabanes , Nathanaël Schaeffer , Henri-Claude Nataf

Observations in polarized emission reveal the existence of large-scale coherent magnetic fields in a wide range of spiral galaxies. Radio-polarization data show that these fields are strongly inclined towards the radial direction, with…

Astrophysics · Physics 2009-11-13 Oliver Gressel , Udo Ziegler , Detlef Elstner , Günther Rüdiger

We demonstrate that a magneto-convection simulation incorporating essential physical processes governing solar surface convection exhibits turbulent small-scale dynamo action. By presenting a derivation of the energy balance equation and…

Solar and Stellar Astrophysics · Physics 2010-04-23 Jonathan Pietarila Graham , Robert Cameron , Manfred Schuessler

We show that in decaying hydromagnetic turbulence with initial kinetic helicity, a weak magnetic field eventually becomes fully helical. The sign of magnetic helicity is opposite to that of the kinetic helicity - regardless of whether or…

It is usually believed that the geo-dynamo of the Earth or more generally of other planets, is created by the convective fluid motions inside their molten cores. An alternative to this thermal or compositional convection can however be…

Fluid Dynamics · Physics 2016-08-16 P. Le Gal , L. Lacaze , S. Le Dizès

To understand the dynamo driven by time-dependent flow, e.g. turbulence, we investigate numerically the dynamo induced by time-periodic force in rotating magnetohydrodynamic flow and focus on the effect of force frequency on the dynamo…

Fluid Dynamics · Physics 2018-03-14 Xing Wei

When an interacting many-body system, such as a magnet, is driven in time by an external perturbation, such as a magnetic field,the system cannot respond instantaneously due to relaxational delay. The response of such a system under a…

Statistical Mechanics · Physics 2009-10-31 Bikas K Chakrabarti , Muktish Acharyya

Polarity reversals are a key feature of Earth's magnetic field, yet the processes governing them are still poorly understood. Dipole reversals have been found in many numerical dynamo simulations and often occur close to the transition…

Geophysics · Physics 2025-05-13 Andrew T. Clarke , Christopher J. Davies , Souvik Naskar , Stephen J. Mason