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We consider the nonaxisymmetric modes of instability present in Taylor-Couette flow under the application of helical magnetic fields, mainly for magnetic Prandtl numbers close to the inductionless limit, and conduct a full examination of…

流体动力学 · 物理学 2015-10-28 Adam Child , Evy Kersalé , Rainer Hollerbach

The transport dynamo mechanism, which describes the magnetic field generation by diffusion flow is reviewed. In this mechanism, the cross-field transport caused by the random motion of fluid breaks the frozen-flux approximation, and the…

流体动力学 · 物理学 2021-10-07 Chang-Mo Ryu

The role of turbulence in current generation and self-excitation of magnetic fields has been studied in the geometry of a mechanically driven, spherical dynamo experiment, using a three dimensional numerical computation. A simple impeller…

等离子体物理 · 物理学 2009-11-11 R. A. Bayliss , C. B. Forest , M. D. Nornberg , E. J. Spence , P. W. Terry

The linear marginal instability of an MHD Taylor-Couette flow of infinite vertical extension is considered. For hydrodynamically unstable flows the minimum Reynolds number exists even without a magnetic field, but there are also solutions…

天体物理学 · 物理学 2016-08-16 G. Rüdiger

We study effects of kinetic helicity fluctuations in a turbulence with large-scale shear using two different approaches: the spectral tau-approximation and the second order correlation approximation (or first-order smoothing approximation).…

天体物理学 · 物理学 2009-06-23 N. Kleeorin , I. Rogachevskii

In systems where the standard $\alpha$ effect is inoperative, one often explains the existence of mean magnetic fields by invoking the `incoherent $\alpha$ effect', which appeals to fluctuations of the mean kinetic helicity at a mesoscale.…

太阳与恒星天体物理 · 物理学 2023-10-24 Kishore Gopalakrishnan , Nishant Singh

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…

天体物理学 · 物理学 2011-02-11 J. Cho , E. Vishniac , A. Beresnyak , A. Lazarian , D. Ryu

A general type of mathematical argument is described, which applies to all the cases in which dynamo maintenance of a steady magnetic field by motion in a uniform density is known to be impossible. Previous work has demonstrated that…

天体物理学 · 物理学 2007-05-23 A. Mangalam

We investigate numerically magnetic field generation by thermal convection with square periodicity cells in a rotating horizontal layer of electrically-conducting fluid with stress-free electrically perfectly conducting boundaries for…

混沌动力学 · 物理学 2010-04-12 V. Zheligovsky

Kinematic dynamo in incompressible isotropic turbulent flows with high magnetic Prandtl number is considered. The approach interpreting an arbitrary magnetic field distribution as a superposition of localized perturbations (blobs) is…

流体动力学 · 物理学 2023-10-26 A. S. Il'yn , A. V. Kopyev , V. A. Sirota , K. P. Zybin

In this paper, we prove the asymptotic stability of Couette flow in a strong uniform magnetic field for the Euler-MHD system, when the perturbations are in Gevrey-$\frac{1}{s}$, $(\frac12<s\leq 1)$ and of size smaller than the resistivity…

偏微分方程分析 · 数学 2023-05-09 Weiren Zhao , Ruizhao Zi

We study the stability of a compressible magnetic plane Couette flow and show that compressibility profoundly alters the stability properties if the magnetic field has a component perpendicular to the direction of flow. The necessary…

天体物理学 · 物理学 2008-11-26 Alfio Bonanno , Vadim Urpin

We have performed numerical simulations of boundary-driven dynamos using a three-dimensional non-linear magnetohydrodynamical model in a spherical shell geometry. A conducting fluid of magnetic Prandtl number Pm=0.01 is driven into motion…

流体动力学 · 物理学 2012-11-02 Céline Guervilly , Nicholas H. Brummell

Here, an analytical version of numerical results is obtained in case of considering the laminar non-turbulent limit, of a twisted Riemannian thin flux tube. It is shown that the magnetic field is amplified, when electric current helicity…

流体动力学 · 物理学 2009-06-30 Garcia de Andrade

With materials of anisotropic electrical conductivity, it is possible to generate a dynamo with a simple velocity field, of the type precluded by Cowling's theorems with isotropic materials. Following a previous study by Ruderman and…

地球物理 · 物理学 2020-04-28 Thierry Alboussiere , Kamel Drif , Franck Plunian

A novel large-scale dynamo mechanism, the magnetic shear-current effect, is discussed and explored. The effect relies on the interaction of magnetic fluctuations with a mean shear flow, meaning the saturated state of the small-scale dynamo…

高能天体物理现象 · 物理学 2016-06-22 Jonathan Squire , Amitava Bhattacharjee

In this paper, the generation of magnetic fields in a nonuniformly rotating layer of finite thickness of an electrically conducting fluid by thermomagnetic (TM) instability. This instability arises due to the temperature gradient $\nabla…

流体动力学 · 物理学 2021-04-23 M. I. Kopp , K. N. Kulik , A. V. Tur , V. V. Yanovsky

We study the 3D magnetohydrodynamics (MHD) equations in an annular cylinder, perturbed around the explicit steady state given by the 3D Taylor-Couette velocity field and zero magnetic field. Combining a recent linear instability result for…

偏微分方程分析 · 数学 2025-10-15 Víctor Navarro-Fernández , David Villringer

We report the results of a complete modal and nonmodal linear stability analysis of the electrohydrodynamic flow (EHD) for the problem of electroconvection in the strong injection region. Convective cells are formed by Coulomb force in an…

流体动力学 · 物理学 2015-06-24 Mengqi Zhang , Fulvio Martinelli , Jian Wu , Peter J. Schmid , Maurizio Quadrio

Generation of magnetic field energy, without mean field generation, is studied. Isotropic mirror-symmetric turbulence of a conducting fluid amplifies the energy of small-scale magnetic perturbations if the magnetic Reynolds number is high,…

天体物理学 · 物理学 2008-11-26 A. Gruzinov , S. Cowley , R. Sudan