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The generation of mean magnetic fields is studied for a simple non-helical flow where a net cross helicity of either sign can emerge. This flow, which is also known as the Archontis flow, is a generalization of the…

Solar and Stellar Astrophysics · Physics 2009-10-10 Sharanya Sur , Axel Brandenburg

We propose a plasma experiment to be used to investigate fundamental properties of astrophysical dynamos. The highly conducting, fast-flowing plasma will allow experimenters to explore systems with magnetic Reynolds numbers an order of…

Plasma Physics · Physics 2015-05-13 E. J. Spence , K. Reuter , C. B. Forest

Spin torques, that is, effects of conduction electrons on magnetization dynamics, are calculated microscopically in the first order in spatial gradient and time derivative of magnetization. Special attention is paid to the so-called…

Mesoscale and Nanoscale Physics · Physics 2015-06-25 H. Kohno , G. Tatara , J. Shibata , Y. Suzuki

The solution of the mean spherical approximation (MSA) integral equation for isotropic multicomponent dipolar hard sphere fluids without external fields is used to construct a density functional theory (DFT), which includes external fields,…

Statistical Mechanics · Physics 2015-05-28 I. Szalai , S. Dietrich

A mean-field theory of the electrodynamics of a turbulent fluid is formulated under the assumption that the molecular electric conductivity is correlated with the turbulent velocity fluctuation in the (radial) direction, $\mathbf{g}$. It is…

Fluid Dynamics · Physics 2023-05-03 Oliver Gressel , Günther Rüdiger , Detlef Elstner

Noting that two-dimensional magnetohydrodynamics can be modeled by conformal field theory, we argue that when the Alf'ven effect is also taken into account one is naturally lead to consider conformal field theories, which have logarithmic…

High Energy Physics - Theory · Physics 2008-02-03 M. R. Rahimi Tabar , S. Rouhani

Mechanisms of nonhelical large-scale dynamos (shear-current dynamo and effect of homogeneous kinetic helicity fluctuations with zero mean) in a homogeneous turbulence with large-scale shear are discussed. We have found that the…

Astrophysics · Physics 2009-11-13 I. Rogachevskii , N. Kleeorin

A model for the solar dynamo, consistent in global flow and numerical method employed with the differential rotation model, is developed. The magnetic turbulent diffusivity is expressed in terms of the entropy gradient, which is controlled…

Solar and Stellar Astrophysics · Physics 2017-06-28 L. L. Kitchatinov , A. A. Nepomnyashchikh

A simple analytical relation of form {\alpha} = 2 {\kappa} -1 between the magnetic energy spectral exponent {\alpha} of the turbulent magnetic field in the solar photosphere and its magnetic flux cancellation exponent {\kappa}, valid under…

Solar and Stellar Astrophysics · Physics 2014-04-08 G. Marschalkó , K. Petrovay

A conservative coupled finite difference-boundary element computational procedure for the simulation of turbulent magnetohydrodynamic flow in a straight rectangular duct at finite magnetic Reynolds number is presented. The flow is assumed…

Fluid Dynamics · Physics 2015-11-05 Vinodh Bandaru , Thomas Boeck , Dmitry Krasnov , Jörg Schumacher

This article is focused on the dynamics of a rotating electrically conducting fluid in a turbulent state. As inside the Earth's core or in various industrial processes, a flow is altered by the presence of both background rotation and a…

Fluid Dynamics · Physics 2011-04-01 Benjamin F. N. Favier , Fabien S. Godeferd , Claude Cambon

We consider stability of regimes of hydromagnetic thermal convection in a rotating horizontal layer with free electrically conducting boundaries, to perturbations involving large spatial and temporal scales. Equations governing the…

Chaotic Dynamics · Physics 2009-11-13 V. Zheligovsky

Using direct numerical simulations of the equations of magnetohydrodynamics, we study reversals of the magnetic field generated by the flow of an electrically conducting fluid in a sphere. We show that at low magnetic Prandtl numbers,…

Fluid Dynamics · Physics 2015-06-17 Pankaj Mishra , Christophe Gissinger , Emmanuel Dormy , Stephan Fauve

We present a three--pronged numerical approach to the dynamo problem at low magnetic Prandtl numbers $P_M$. The difficulty of resolving a large range of scales is circumvented by combining Direct Numerical Simulations, a Lagrangian-averaged…

Geophysics · Physics 2009-11-10 Y. Ponty , P. D. Mininni , D. C. Montgomery , J. -F. Pinton , H. Politano , A. Pouquet

A conducting Taylor-Couette flow with quasi-Keplerian rotation law containing a toroidal magnetic field serves as a mean-field dynamo model of the Tayler-Spruit-type. The flows are unstable against nonaxisymmetric perturbations which form…

Solar and Stellar Astrophysics · Physics 2020-02-12 G. Rüdiger , M. Schultz

We add the $\alpha-$ effect in the dynamo driven accretion disk model proposed by Tout & Pringle (1992), i.e., a dynamo model depends on the physical processes such as Parker instability, Balbus-Hawley instability, magnetic field…

Astrophysics · Physics 2007-05-23 Chun-yu Ma , Peter L Biermann

Context: Direct numerical simulations have shown that the dynamo is efficient even at low Prandtl numbers, i.e., the critical magnetic Reynolds number Rm_c necessary for the dynamo to be efficient becomes smaller than the hydrodynamic…

Plasma Physics · Physics 2011-11-11 Eric Buchlin

A strong toroidal field can exist in form of a magnetic layer in the overshoot region below the solar convection zone. This motivates a more detailed study of the magnetic buoyancy instability with rotation. We calculate the alpha effect…

Solar and Stellar Astrophysics · Physics 2011-10-04 Piyali Chatterjee , Dhrubaditya Mitra , Matthias Rheinhardt , Axel Brandenburg

Stochastic simulations are used to create synthetic one-dimensional telegraph approximation (TA) signals based on turbulent zero crossings, where the interval between crossings is governed by a power law probability distribution with…

Data Analysis, Statistics and Probability · Physics 2022-12-16 Michael Heisel

At large magnetic Reynolds numbers, magnetic helicity evolution plays an important role in astrophysical large-scale dynamos. The recognition of this fact led to the development of the dynamical alpha quenching formalism, which predicts…

Solar and Stellar Astrophysics · Physics 2012-03-08 Alexander Hubbard , Axel Brandenburg
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