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Here, we present numerical simulations of magnetic flux buoyantly rising from a granular convection zone into the low corona. We study the complex interaction of the magnetic field with the turbulent plasma. The model includes the radiative…

Space Physics · Physics 2015-05-18 Fang Fang , Ward Manchester , William P. Abbett , Bart van der Holst

A three-dimensional numerical computation of magnetohydrodynamic dynamo behavior is described. The dynamo is mechanically forced with a driving term of the Taylor-Green type. The magnetic field development is followed from negligibly small…

Astrophysics · Physics 2007-05-23 P. D. Mininni , Y. Ponty , D. C. Montgomery , J. -F. Pinton , H. Politano , A. Pouquet

We re-examine the nature of the turbulent magnetic diffusivity tensor of mean field electrodynamics and show that an inconsistency arises if it is calculated via consideration of time-independent magnetic fields. Specifically, the predicted…

Solar and Stellar Astrophysics · Physics 2010-01-14 David W. Hughes , Michael R. E. Proctor

Recent numerical simulations of dynamo action resulting from rotating convection have revealed some serious problems in applying the standard picture of mean field electrodynamics at high values of the magnetic Reynolds number, and have…

Solar and Stellar Astrophysics · Physics 2013-02-20 D. W. Hughes , M. R. E. Proctor

Context. Earlier work has suggested that large-scale dynamos can reach and maintain equipartition field strengths on a dynamical time scale only if magnetic helicity of the fluctuating field can be shed from the domain through open…

Solar and Stellar Astrophysics · Physics 2011-07-08 P. J. Käpylä , M. J. Korpi , A. Brandenburg

A physically consistent approach is considered for defining an external magnetic field as needed in computational fluid dynamics problems involving magnetohydrodynamics (MHD). The approach results in simple analytical formulae that can be…

Fluid Dynamics · Physics 2009-11-25 E. V. Votyakov , S. C. Kassinos , X. Albets-Chico

The spatial correlation function of the momentum density in the three-dimensional dilute sheared granular fluids is theoretically investigated. The existence of the long-range correlation is verified through both the analytic calculation…

Statistical Mechanics · Physics 2009-11-13 Michio Otsuki , Hisao Hayakawa

The fast rates of magnetic reconnection found in both nature and experiments are important to understand theoretically. Recently, it was demonstrated that two-fluid magnetic reconnection remains fast in the strong guide field regime,…

Plasma Physics · Physics 2015-05-20 A. Stanier , Andrei N. Simakov , L. Chacon , W. Daughton

Fluctuation dynamo action has been obtained for a flow previously used to model fluid turbulence, where the sensitivity of the magnetic field parameters to the kinetic energy spectrum can be explored. We apply quantitative morphology…

Astrophysics · Physics 2008-11-26 S. Louise Wilkin , Carlo F. Barenghi , Anvar Shukurov

The turbulent dynamo effect, which describes the generation of magnetic fields in astrophysical objects, is described by the dynamo equation. This, in the kinematic (linear) approximation gives an unbounded exponential growth of the long…

Chaotic Dynamics · Physics 2007-05-23 Abhik Basu

We investigate analytically the magnetic instability in a rotating and electrically conducting fluid induced by an imposed magnetic field with its associated electric current. The short-wavelength approximation is used in the linear…

Earth and Planetary Astrophysics · Physics 2013-08-22 Xing Wei

We use numerical simulations to study the flow of athermal, frictionless, soft-core two dimensional spherocylinders driven by a uniform steady-state simple shear applied at a fixed volume and a fixed finite strain rate $\dot\gamma$. Energy…

Soft Condensed Matter · Physics 2020-03-30 Theodore A. Marschall , S. Teitel

The turbulent magnetic diffusivity tensor is determined in the presence of rotation or shear. The question is addressed whether dynamo action from the shear-current effect can explain large-scale magnetic field generation found in…

Astrophysics · Physics 2010-11-05 A. Brandenburg , K. -H. Rädler , M. Rheinhardt , P. J. Käpylä

Numerical simulations of forced turbulence in elongated shearing boxes are carried out to demonstrate that a nonhelical turbulence in conjunction with a linear shear can give rise to a mean-field dynamo. Exponential growth of magnetic field…

Magnetic helicity has risen to be a major player in dynamo theory, with the helicity of the small-scale field being linked to the dynamo saturation process for the large-scale field. It is a nearly conserved quantity, which allows its…

Solar and Stellar Astrophysics · Physics 2011-01-04 Alexander Hubbard , Axel Brandenburg

The role of turbulence in current generation and self-excitation of magnetic fields has been studied in the geometry of a mechanically driven, spherical dynamo experiment, using a three dimensional numerical computation. A simple impeller…

Plasma Physics · Physics 2009-11-11 R. A. Bayliss , C. B. Forest , M. D. Nornberg , E. J. Spence , P. W. Terry

Kinetic helicity is a fundamental characteristics of astrophysical turbulent flows. It is not only responsible for the generation of large-scale magnetic fields in the Sun, stars, and spiral galaxies, but it also affects turbulent diffusion…

Fluid Dynamics · Physics 2025-05-15 Igor Rogachevskii , Nathan Kleeorin , Axel Brandenburg

Initial results from the Madison Dynamo Experiment provide details of the inductive response of a turbulent flow of liquid sodium to an applied magnetic field. The magnetic field structure is reconstructed from both internal and external…

Plasma Physics · Physics 2007-05-23 M. D. Nornberg , E. J. Spence , R. D. Kendrick , C. M. Jacobson , C. B. Forest

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

The kinematic dynamo problem is investigated for the flow of a conducting fluid in a cylindrical, periodic tube with conducting walls. The methods used are an eigenvalue analysis of the steady regime, and the three-dimensional solution of…

Astrophysics · Physics 2009-11-07 Wolfgang Dobler , Peter Frick , Rodion Stepanov