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Using simulations of helically driven turbulence, it is shown that the ratio of kinetic to magnetic energy dissipation scales with the magnetic Prandtl number in power law fashion with an exponent of approximately 0.6. Over six orders of…

Solar and Stellar Astrophysics · Physics 2011-05-16 A. Brandenburg

Small-scale dynamos are expected to operate in all astrophysical fluids that are turbulent and electrically conducting, for example the interstellar medium, stellar interiors, and accretion disks, where they may also be affected by or…

Fluid Dynamics · Physics 2018-07-19 A. Brandenburg , N. E. L. Haugen , Xiang-Yu Li , K. Subramanian

Several recent advances in turbulent dynamo theory are reviewed. High resolution simulations of small-scale and large-scale dynamo action in periodic domains are compared with each other and contrasted with similar results at low magnetic…

Solar and Stellar Astrophysics · Physics 2012-07-10 Axel Brandenburg , Dmitry Sokoloff , Kandaswamy Subramanian

Using direct simulations of hydromagnetic turbulence driven by random polarized waves it is shown that dynamo action is possible over a wide range of magnetic Prandtl numbers from 10^-3 to 1. Triply periodic boundary conditions are being…

Astrophysics · Physics 2010-01-15 Axel Brandenburg

We investigate the dynamo problem in the limit of small magnetic Prandtl number ($\Pm$) using a shell model of magnetohydrodynamic turbulence. The model is designed to satisfy conservation laws of total energy, cross helicity and magnetic…

Fluid Dynamics · Physics 2007-05-23 Rodion Stepanov , Franck Plunian

Saturated small-scale dynamo solutions driven by isotropic non-helical turbulence are presented at low magnetic Prandtl numbers Pm down to 0.01. For Pm < 0.1, most of the energy is dissipated via Joule heat and, in agreement with earlier…

Solar and Stellar Astrophysics · Physics 2011-10-25 Axel Brandenburg

We present numerical investigations into three principal properties of the small-scale dynamo in stably stratified turbulence: the onset criterion, the growth rate, and the nature of the magnetic field anisotropy in the kinematic regime.…

Fluid Dynamics · Physics 2021-02-04 Valentin Skoutnev , Jonathan Squire , Amitava Bhattacharjee

We present an MHD shell model suitable for computation of various energy fluxes of magnetohydrodynamic turbulence for very small and very large magnetic Prandtl numbers $\mathrm{Pm}$; such computations are inaccessible to direct numerical…

Fluid Dynamics · Physics 2016-09-21 Mahendra K. Verma , Rohit Kumar

The small-scale dynamo is a process by which turbulent kinetic energy is converted into magnetic energy, and thus is expected to depend crucially on the nature of turbulence. In this work, we present a model for the small-scale dynamo that…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Jennifer Schober , Dominik Schleicher , Christoph Federrath , Ralf Klessen , Robi Banerjee

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

In astrophysical situations, e.g. in the interstellar medium (ISM), neutrals can provide viscous damping on scales much larger than the magnetic diffusion scale. Through numerical simulations, we have found that the magnetic field can have…

Astrophysics · Physics 2009-11-07 Jungyeon Cho , A. Lazarian , Ethan Vishniac

Planetary and stellar dynamos likely result from turbulent motions in magnetofluids with kinematic viscosities that are small compared to their magnetic diffusivities. Laboratory experiments are in progress to produce similar dynamos in…

Astrophysics · Physics 2009-11-11 P. D. Mininni

In this study we discuss two key issues related to a small-scale dynamo instability at low magnetic Prandtl numbers and large magnetic Reynolds numbers, namely: (i) the scaling for the growth rate of small-scale dynamo instability in the…

Solar and Stellar Astrophysics · Physics 2015-06-03 N. Kleeorin , I. Rogachevskii

The dynamics of small-scale structures in free-surface turbulence is crucial to large-scale phenomena in natural and industrial environments. Here we conduct experiments on the quasi-flat free surface of a zero-mean-flow turbulent water…

Fluid Dynamics · Physics 2025-03-14 Yinghe Qi , Yaxing Li , Filippo Coletti

Small-scale dynamo action is often held responsible for the generation of quiet-Sun magnetic fields. We aim to determine the excitation conditions and saturation level of small-scale dynamos in non-rotating turbulent convection at low…

Solar and Stellar Astrophysics · Physics 2018-06-06 Petri J. Käpylä , Maarit J. Käpylä , Axel Brandenburg

Amplification of magnetic field due to kinematic turbulent dynamo action is studied in the regime of small magnetic Prandtl numbers. Such a regime is relevant for planets and stars interiors, as well as for liquid metal laboratory…

Solar and Stellar Astrophysics · Physics 2015-05-20 Leonid M. Malyshkin , Stanislav Boldyrev

In this article we review small-scale dynamo processes that are responsible for magnetic field generation on scales comparable to and smaller than the energy carrying scales of turbulence. We provide a review of critical observation of…

Solar and Stellar Astrophysics · Physics 2023-07-19 Matthias Rempel , Tanayveer Bhatia , Luis Bellot Rubio , Maarit J. Korpi-Lagg

Magnetic fields are critical at many scales to galactic dynamics and structure, including multiphase pressure balance, dust processing, and star formation. Dynamo action determines their dynamical structure and strength. Simulations of…

Astrophysics of Galaxies · Physics 2026-02-17 Frederick A. Gent , Mordecai-Mark Mac Low , Maarit J. Korpi-Lagg , Touko Puro , Matthias Reinhardt

(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

We report an extensive numerical study of the small-scale turbulent dynamo at large magnetic Prandtl numbers Pm. A Pm scan is given for the model case of low-Reynolds-number turbulence. We concentrate on three topics: magnetic-energy…

Astrophysics · Physics 2008-11-26 A. A. Schekochihin , S. C. Cowley , S. F. Taylor , J. L. Maron , J. C. McWilliams
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