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Direct numerical simulations of turbulent Hall dynamos are presented. The evolution of an initially weak and small scale magnetic field in a system maintained in a stationary turbulent regime by a stirring force at a macroscopic scale is…

Astrophysics · Physics 2009-11-10 P. D. Mininni , D. O. Gómez , S. M. Mahajan

Numerical solutions of the incompressible magnetohydrodynamic (MHD) equations are reported for the interior of a rotating, perfectly-conducting, rigid spherical shell that is insulator-coated on the inside. A previously-reported spectral…

Fluid Dynamics · Physics 2009-11-13 P. D. Mininni , D. C. Montgomery , L. Turner

We present the results of our detailed pseudospectral direct numerical simulation (DNS) studies, with up to $1024^3$ collocation points, of incompressible, magnetohydrodynamic (MHD) turbulence in three dimensions, without a mean magnetic…

Chaotic Dynamics · Physics 2011-01-31 Ganapati Sahoo , Prasad Perlekar , Rahul Pandit

The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly-compressible, supersonic…

Astrophysics of Galaxies · Physics 2014-12-05 Christoph Federrath , Jennifer Schober , Stefano Bovino , Dominik R. G. Schleicher

We demonstrate that there is an optimal forcing length scale for low Prandtl number dynamo flows, that can significantly reduce the required energy injection rate. The investigation is based on simulations of the induction equation in a…

Fluid Dynamics · Physics 2016-02-24 Mira Sadek , Alexandros Alexakis , Stephan Fauve

We perform fully kinetic simulations of flows known to produce dynamo in magnetohydrodynamics (MHD), considering scenarios with low Reynolds number and high magnetic Prandtl number, relevant for galaxy cluster scale fluctuation dynamos. We…

We investigate the Lagrangian mechanism of the kinematic ``fluctuation'' magnetic dynamo in turbulent plasma flow at small magnetic Prandtl numbers. The combined effect of turbulent advection and plasma resistivity is to carry infinitely…

Plasma Physics · Physics 2015-05-13 Gregory L. Eyink , Antonio F. Neto

The origin of strong magnetic fields in the Universe can be explained by amplifying weak seed fields via turbulent motions on small spatial scales and subsequently transporting the magnetic energy to larger scales. This process is known as…

Variational turbulence is among the few approaches providing rigorous results in turbulence. In addition, it addresses a question of direct practical interest, namely the rate of energy dissipation. Unfortunately, only an upper bound is…

Fluid Dynamics · Physics 2009-10-28 Thierry Alboussiere

We consider the problem of incompressible, forced, nonhelical, homogeneous and isotropic MHD turbulence with no mean magnetic field and large magnetic Prandtl number. This type of MHD turbulence is the end state of the turbulent dynamo,…

We analyze the initial, kinematic stage of magnetic field evolution in an isotropic and homogeneous turbulent conducting fluid with a rough velocity field, v(l) ~ l^alpha, alpha<1. We propose that in the limit of small magnetic Prandtl…

Astrophysics · Physics 2007-05-23 Stanislav Boldyrev , Fausto Cattaneo

Magnetized turbulence is ubiquitous in many astrophysical and terrestrial plasmas but no universal theory exists. Even the detailed energy dynamics in magnetohydrodynamic (MHD) turbulence are still not well understood. We present a suite of…

Astrophysics of Galaxies · Physics 2023-02-06 Philipp Grete , Brian W. O'Shea , Kris Beckwith

(Abridged) The small-scale dynamo may play a substantial role in magnetizing the Universe under a large range of conditions, including subsonic turbulence at low Mach numbers, highly supersonic turbulence at high Mach numbers and a large…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Dominik R. G. Schleicher , Jennifer Schober , Christoph Federrath , Stefano Bovino , Wolfram Schmidt

For more than 40 years the quest to understand how large-scale magnetic fields emerge from turbulent flows in rotating astrophysical systems, such as the Sun, has been a major focus of computational astrophysics research. Using a parameter…

Solar and Stellar Astrophysics · Physics 2026-02-25 François Rincon

We investigate the structure of magnetic field amplified by turbulent velocity fluctuations, in the framework of the kinematic Kazantsev-Kraichnan model. We consider Kolmogorov distribution of velocity fluctuations, and assume that both…

Astrophysics · Physics 2010-01-15 Leonid Malyshkin , Stanislav Boldyrev

The self-excitation of magnetic field by a spiral Couette flow between two coaxial cylinders is considered. We solve numerically the fully nonlinear, three-dimensional MHD equations for magnetic Prandtl numbers Pm (ratio of kinematic…

Astrophysics · Physics 2009-11-06 Wolfgang Dobler , Anvar Shukurov , Axel Brandenburg

We study a simple magnetohydrodynamical approach in which hydrodynamics and MHD turbulence are coupled in a shell model, with given dynamo constrains in the large scales. We consider the case of a low Prandtl number fluid for which the…

Earth and Planetary Astrophysics · Physics 2015-05-13 Roberto Benzi , Jean-Francois Pinton

We present an analysis of data stemming from numerical simulations of decaying magnetohydrodynamic (MHD) turbulence up to grid resolution of 1536^3 points and up to Taylor Reynolds number of 1200. The initial conditions are such that the…

Solar and Stellar Astrophysics · Physics 2015-05-13 P. D. Mininni , A. Pouquet

Accurate magnetohydrodynamical (MHD) turbulence simulations require understanding numerical dissipation. We quantify numerical viscosity and resistivity in subsonic (M=0.1) and supersonic (M=10) turbulence regimes. The hydrodynamic (Re) and…

Solar and Stellar Astrophysics · Physics 2025-01-31 Lakshmi Malvadi Shivakumar , Christoph Federrath

The intracluster medium of galaxy clusters is an extremely hot and diffuse, nearly collisionless plasma, which hosts dynamically important magnetic fields of $\sim \mu {\rm G}$ strength. Seed magnetic fields of much weaker strength of…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-17 Radhika Achikanath Chirakkara , Amit Seta , Christoph Federrath , Matthew W. Kunz