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The effect of a dynamo-generated mean magnetic field of Beltrami type on the mean electromotive force is studied. In the absence of the mean magnetic field the turbulence is assumed to be homogeneous and isotropic, but it becomes…

Astrophysics · Physics 2008-10-20 A. Brandenburg , K. -H. Rädler , M. Rheinhardt , K. Subramanian

The purpose of this work was to obtain diffusion coefficient for the magnetic angular momentum transport and material transport in a rotating solar model. We assumed that the transport of both angular momentum and chemical elements caused…

Astrophysics · Physics 2008-05-26 W. M. Yang , S. L. Bi

The motion of energetic particles in magnetic turbulence across a mean magnetic field is explored analytically. The approach presented here allows for a full time-dependent description of the transport, including compound sub-diffusion. The…

Plasma Physics · Physics 2017-05-24 Andreas Shalchi

A plane-shear flow in a fluid with forced turbulence is considered. If the fluid is electrically-conducting then a mean electromotive force (EMF) results even without basic rotation and the magnetic diffusivity becomes a highly anisotropic…

Astrophysics · Physics 2009-11-11 G. Ruediger , L. L. Kitchatinov

To understand the basic mechanism of the formation of magnetic flux concentrations, we determine by direct numerical simulations the turbulence contributions to the mean magnetic pressure in a strongly stratified isothermal layer with large…

Solar and Stellar Astrophysics · Physics 2015-03-17 Axel Brandenburg , Koen Kemel , Nathan Kleeorin , Igor Rogachevskii

Imposing a magnetic field on a turbulent flow of electrically conducting fluid incurs the Joule effect. A current paradigm is that the corresponding dissipation increases with the intensity of the magnetic field, and as a result turbulent…

Fluid Dynamics · Physics 2017-07-05 Alban Pothérat , Rico Klein

Rotation modulates turbulence causing columnar structuring of a turbulent flow in case of sufficiently strong rotation. This yields significant changes in the flow characteristics and dispersion properties, which makes rotational turbulence…

Chaotic Dynamics · Physics 2009-04-07 Arkadiusz K. Kuczaj , Bernard J. Geurts , Darryl D. Holm

The flow of an electrically conducting fluid in a thin disc under the action of an azimuthal Lorentz force is studied experimentally. At small forcing, the Lorentz force is balanced by either viscosity or inertia, yielding quasi-Keplerian…

Fluid Dynamics · Physics 2021-09-14 Marlone Vernet , Michael Pereira , Stephan Fauve , Christophe Gissinger

The predictive power of mean-field theory is emphasized by comparing theory with simulations under controlled conditions. The recently developed test-field method is used to extract turbulent transport coefficients both in kinematic as well…

Solar and Stellar Astrophysics · Physics 2011-01-04 A. Brandenburg , P. Chatterjee , F. Del Sordo , A. Hubbard , P. J. Käpylä , M. Rheinhardt

We use direct numerical simulations to compute turbulent transport coefficients for passive scalars in turbulent rotating flows. Effective diffusion coefficients in the directions parallel and perpendicular to the rotations axis are…

Fluid Dynamics · Physics 2013-02-13 P. Rodriguez Imazio , P. D. Mininni

We show for the first time that sustained turbulence is possible at low magnetic Prandtl number for Keplerian flows with no mean magnetic flux. Our results indicate that increasing the vertical domain size is equivalent to increasing the…

Solar and Stellar Astrophysics · Physics 2016-12-21 Farrukh Nauman , Martin E. Pessah

Magnetic turbulence in the solar wind is treated from the point of view of electrodynamics. This can be done based on the use of Poynting's theorem attributing all turbulent dynamics to the spectrum of turbulent conductivity. For two…

Space Physics · Physics 2017-01-19 R. A. Treumann , W. Baumjohann

The transport of charged energetic particles in the presence of strong intermittent heliospheric turbulence is computationally analyzed based on known properties of the interplanetary magnetic field and solar wind plasma at 1 Astronomical…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Fathallah Alouani-Bibi , Jakobus A. le Roux

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…

Fluid Dynamics · Physics 2022-02-24 Ming Yan , Michael A. Calkins

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

Context: Rotating anisotropic convection generates differential rotation in stellar convection zones. Aims: The main aim is to compute the non-diffusive contribution ($\Lambda$ effect) to angular momentum transport, described by Reynolds…

Solar and Stellar Astrophysics · Physics 2026-03-11 P. J. Käpylä

It has recently been shown that a significant slowdown of many stars can be attributed to the emergence of a strong magnetic field within the radiative region, where heat is transferred through radiation in a stably stratified layer. Here,…

Fluid Dynamics · Physics 2023-11-30 Florentin Daniel , Ludovic Petitdemange , Christophe Gissinger

Turbulence with a large magnetic Reyonolds number, generically leads to rapidly growing magnetic noise over and above any mean field. We revisit the dynamics of this fluctuating field, in homogeneous, isotropic, helical turbulence. Assuming…

Astrophysics · Physics 2007-05-23 K. Subramanian

From numerical simulations, we show that non-rotating magnetohydrodynamic shear flows are unstable to finite amplitude velocity perturbations and become turbulent, leading to the growth and sustenance of magnetic energy, including large…

Plasma Physics · Physics 2017-03-10 Farrukh Nauman , Eric G. Blackman

The intense turbulence present in the solar convection zone is a major challenge to both theory and simulation as one tries to understand the origins of the striking differential rotation profile with radius and latitude that has been…

Astrophysics · Physics 2009-11-07 Allan Sacha Brun , Juri Toomre