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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 analyze direct numerical simulations of large-scale dynamos in inhomogeneous nonhelically driven rotating turbulence with and without shear. The forcing is modulated so that the turbulent intensity peaks in the middle of the…

Plasma Physics · Physics 2025-05-02 Axel Brandenburg , Ethan T. Vishniac

Plasma turbulence is a ubiquitous dynamical process that transfers energy across many spatial and temporal scales and affects energetic particle transport. Recent advances in the understanding of compressible magnetohydrodynamic (MHD)…

Solar and Stellar Astrophysics · Physics 2024-02-09 Siqi Zhao , Huirong Yan , Terry Z. Liu , Ka Ho Yuen , Mijie Shi

Small-scale turbulent dynamo is responsible for the amplification of magnetic fields on scales smaller than the driving scale of turbulence in diverse astrophysical media. Most earlier dynamo theories concern the kinematic regime and…

Astrophysics of Galaxies · Physics 2021-06-25 Siyao Xu , Alex Lazarian

Aims: We determine the components of the $\Lambda$-effect tensor that quantifies the contributions to the turbulent momentum transport even for uniform rotation. Methods: Three-dimensional numerical simulations are used to study turbulent…

Astrophysics · Physics 2008-08-22 P. J. Käpylä , A. Brandenburg

Using a closure model for the evolution of magnetic correlations, we uncover an interesting plausible saturated state of the small-scale fluctuation dynamo (SSD) and a novel anology between quantum mechanical tunneling and the generation of…

Astrophysics · Physics 2007-05-23 Kandaswamy Subramanian

Magnetic fields in galaxies are believed to be the result of dynamo amplification of initially weak seed fields, reaching equipartition strength inside the interstellar medium. The small-scale dynamo appears to be a viable mechanism to…

Astrophysics of Galaxies · Physics 2017-08-16 Michael Rieder , Romain Teyssier

Magnetic fields are widely observed in the Universe in virtually all astrophysical objects, from individual stars to entire galaxies, even in the intergalactic medium, but their specific generation has long been debated. Due to the…

Astrophysics of Galaxies · Physics 2017-11-08 Michael Rieder , Romain Teyssier

Magnetic fields on small scales are ubiquitous in the universe. Though they can often be observed in detail, their generation mechanisms are not fully understood. One possibility is the so-called small-scale dynamo (SSD). Prevailing…

Solar and Stellar Astrophysics · Physics 2023-06-08 Jörn Warnecke , Maarit J. Korpi-Lagg , Frederick A. Gent , Matthias Rheinhardt

Most large-scale planetary magnetic fields are thought to be driven by low Rossby number convection of a low magnetic Prandtl number fluid. Here kinematic dynamo action is investigated with an asymptotic, rapidly rotating dynamo model for…

Geophysics · Physics 2016-12-14 Michael A. Calkins , Louie Long , David Nieves , Keith Julien , Steven M. Tobias

The emergence of large-scale magnetic fields observed in the diffuse interstellar medium is explained by a turbulent dynamo. The underlying transport coefficients have previously been extracted from numerical simulations. So far, this was…

Astrophysics of Galaxies · Physics 2015-06-11 Oliver Gressel , Abhijit Bendre , Detlef Elstner

Observations of galaxy clusters show that the intracluster medium (ICM) is likely to be turbulent and is certainly magnetized. The properties of this magnetized turbulence are determined both by fundamental nonlinear magnetohydrodynamic…

Astrophysics · Physics 2008-11-26 A. A. Schekochihin , S. C. Cowley

We present numerical simulations of three-dimensional compressible magnetoconvection in a rotating rectangular box that represents a section of the solar convection zone. The box contains a convectively unstable layer, surrounded by stably…

Astrophysics · Physics 2009-11-07 M. Ossendrijver , M. Stix , A. Brandenburg

We investigate the effects of weakly and strongly stratified turbulent convection on the mean effective Lorentz force, and especially on the mean effective magnetic pressure. Earlier studies with isotropically forced non-stratified and…

Solar and Stellar Astrophysics · Physics 2012-05-15 P. J. Käpylä , A. Brandenburg , N. Kleeorin , M. J. Mantere , I. Rogachevskii

The contribution of small scale turbulent fluctuations to the induction of mean magnetic field is investigated in our liquid sodium spherical Couette experiment with an imposed magnetic field.An inversion technique is applied to a large…

Fluid Dynamics · Physics 2015-10-06 Simon Cabanes , Nathanaël Schaeffer , Henri-Claude Nataf

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

We present numerical simulations of driven magnetohydrodynamic (MHD) turbulence with weak/moderate imposed magnetic fields. The main goal is to clarify dynamics of magnetic field growth. We also investigate the effects of the imposed…

Astrophysics · Physics 2011-02-11 J. Cho , E. Vishniac , A. Beresnyak , A. Lazarian , D. Ryu

Small amplitude oscillations are a commonly observed feature in prominences/filaments. These oscillations appear to be of local nature, are associated to the fine structure of prominence plasmas, and simultaneous flows and counterflows are…

Solar and Stellar Astrophysics · Physics 2015-05-18 I. Arregui , J. L. Ballester

Magnetic fluctuations generated by a tangling of the mean magnetic field by velocity fluctuations are studied in a developed turbulent convection with large magnetic Reynolds numbers. We show that the energy of magnetic fluctuations depends…

Astrophysics · Physics 2008-11-26 I. Rogachevskii , N. Kleeorin

In magnetohydrodynamic (MHD) turbulence, the large-scale magnetic field sets a preferred local direction for the small-scale dynamics, altering the statistics of turbulence from the isotropic case. This happens even in the absence of a…

Plasma Physics · Physics 2017-05-10 Vladimir Zhdankin , Stanislav Boldyrev , Joanne Mason