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We numerically study the effects of varying electric conductivity and magnetic permeability of the bounding wall on a kinematic dynamo in a sphere for parameters relevant to Madison plasma dynamo experiment (MPDX). The dynamo is excited by…

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

We develop a magnetic ribbon model for molecular cloud filaments. These result from turbulent compression in a molecular cloud in which the background magnetic field sets a preferred direction. We use our model to calculate a synthetic…

Astrophysics of Galaxies · Physics 2017-03-17 Sayantan Auddy , Shantanu Basu , Takahiro Kudoh

Fluctuations of the alpha-effect which break equatorial symmetry of the flow in the kinematic Parker's dynamo are considered. We show, that even small (a few percents) fluctuation can leed to the substantial assymmetry of the magnetic field…

Fluid Dynamics · Physics 2011-10-03 M. Reshetnyak , D. Sokoloff

Carbon nanotubes and biological filaments each spontaneously assemble into kinked helices, rings, and "tennis racket" shapes due to competition between elastic and interfacial effects. We show that the slender geometry is a more important…

Soft Condensed Matter · Physics 2009-11-10 Adam E. Cohen , L. Mahadevan

Solid state theory, density functional theory and its generalizations for correlated systems together with numerical simulations on supercomputers allow nowadays to model magnetic systems realistically and in detail and can be even used to…

Materials Science · Physics 2023-10-16 Vladislav Borisov

The Lagrangian properties of the velocity field in a magnetized fluid are studied using three-dimensional simulations of a helical magnetohydrodynamic dynamo. We compute the attracting and repelling Lagrangian coherent structures, which are…

Solar and Stellar Astrophysics · Physics 2012-07-10 Erico L. Rempel , Abraham C. -L. Chian , Axel Brandenburg

Magnetic fields are important for accretion disc structure. Magnetic fields in a disc system may be transported with the accreted matter. They can be associated with either the central body and/or jet, and be fossil or dynamo excited in…

High Energy Astrophysical Phenomena · Physics 2016-03-23 David Moss , Dmitri Sokoloff , Valery Suleimanov

We review the results obtained by three successful fluid dynamo experiments and discuss what has been learnt from them about the effect of turbulence on the dynamo threshold and saturation. We then discuss several questions that are still…

Fluid Dynamics · Physics 2009-11-13 F. Petrelis , N. Mordant , S. Fauve

We present high resolution 2D and 3D simulations of magnetized decaying turbulence in relativistic resistive magneto-hydrodynamics. The simulations show dynamic formation of large scale intermittent long-lived current sheets being disrupted…

High Energy Astrophysical Phenomena · Physics 2021-12-22 Alexander Chernoglazov , Bart Ripperda , Alexander A. Philippov

Various aspects of the magnetism of the quiet sun are reviewed. The suggestion that a small scale dynamo acting at granular scales generates what we call the quiet sun fields is studied in some detail. Although dynamo action has been proved…

Solar and Stellar Astrophysics · Physics 2015-06-12 V. Martinez Pillet

We perform numerical simulation of dynamo with magnetic Prandtl number $\mathrm{Pm} =0.2$ on $1024^3$ grid, and compute the energy fluxes and the shell-to-shell energy transfers. These computations indicate that the magnetic energy growth…

Fluid Dynamics · Physics 2015-06-26 Rohit Kumar , Mahendra K. Verma , Ravi Samtaney

We introduce six families of three-dimensional space-periodic steady solenoidal flows, whose kinetic helicity density is zero at any point. Four families are analytically defined. Flows in four families have zero helicity spectrum. Sample…

Fluid Dynamics · Physics 2018-04-06 A. Rasskazov , R. Chertovskih , V. Zheligovsky

We present the first demonstration of the negative effective magnetic pressure instability in direct numerical simulations of stably stratified, externally forced, isothermal hydromagnetic turbulence in the regime of large plasma beta. By…

Solar and Stellar Astrophysics · Physics 2011-10-05 Axel Brandenburg , Koen Kemel , Nathan Kleeorin , Dhrubaditya Mitra , Igor Rogachevskii

In strongly compressible magnetohydrodynamic turbulence, obliqueness between the large-scale density gradient and magnetic field gives an electromotive force mediated by density variance (intensity of density fluctuation). This effect is…

Solar and Stellar Astrophysics · Physics 2022-05-31 Nobumitsu Yokoi , Steven M. Tobias

Relaminarization of wall-bounded turbulent flows by means of external static magnetic fields is a long-known phenomenon in the physics of electrically conducting fluids at low magnetic Reynolds numbers. Despite the large literature on the…

Fluid Dynamics · Physics 2020-05-06 L. Moriconi

We introduce on/off intermittency into a mean field dynamo model by imposing stochastic fluctuations in either the alpha effect or through the inclusion of a fluctuating electromotive force. Sufficiently strong small scale fluctuations with…

Astrophysics · Physics 2008-03-27 A. Brandenburg , E. A. Spiegel

Kinetic helicity is a fundamental characteristics of astrophysical turbulent flows. It is not only responsible for the generation of large-scale magnetic fields in the Sun, stars, and spiral galaxies, but it also affects turbulent diffusion…

Fluid Dynamics · Physics 2025-05-15 Igor Rogachevskii , Nathan Kleeorin , Axel Brandenburg

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

In this manuscript using the asymptotic method of multiscale nonlinear theory we construct a nonlinear theory of the appearance of large-scale structures in the stratified conductive medium with the presence of small-scale oscillations of…

Earth and Planetary Astrophysics · Physics 2016-12-30 M. I. Kopp , A. V. Tur , V. V. Yanovsky