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The effect of magnetic shear and shear flow on local gravitationally induced instabilities is investigated. A simple model is constructed allowing for an arbitrary entropy gradient and a shear plasma flow in the Boussinesq approximation. A…

Astrophysics · Physics 2009-11-06 Gregory G. Howes , Steven C. Cowley , James C. McWilliams

The effects of uniform horizontal shear on a stably stratified layer of gas is studied. The system is initially destabilized by a magnetically buoyant flux tube pointing in the cross-stream direction. The shear amplifies the initial field…

Solar and Stellar Astrophysics · Physics 2014-11-20 Violaine Vermersch , Axel Brandenburg

Straining of magnetic fields by large-scale shear flow, generally assumed to lead to intensification and generation of small scales, is re-examined in light of the persistent observation of large-scale magnetic fields in astrophysics. It is…

Plasma Physics · Physics 2022-07-20 B. Tripathi , A. E. Fraser , P. W. Terry , E. G. Zweibel , M. J. Pueschel

Within the framework of shallow-water magnetohydrodynamics, we investigate the linear instability of horizontal shear flows, influenced by an aligned magnetic field and stratification. Various classical instability results, such as…

Fluid Dynamics · Physics 2016-01-15 Julian Mak , Stephen D. Griffiths , D. W. Hughes

Motivated by the interface model for the solar dynamo, this paper explores the complex magnetohydrodynamic interactions between convective flows and shear-driven instabilities. Initially, we consider the dynamics of a forced shear flow…

Solar and Stellar Astrophysics · Physics 2015-05-13 L. J. Silvers , P. J. Bushby , M. R. E. Proctor

We investigate the effects of ambipolar diffusion and the Hall effect on the stability of weakly-ionized, magnetized planar shear flows. Employing a local approach similar to the shearing-sheet approximation, we solve for the evolution of…

Astrophysics · Physics 2009-11-13 Matthew W. Kunz

Macroscopic gas motions are widespread throughout the solar atmosphere and shearing motions couple to the non--ideal effects, destabilising low frequency fluctuations in the medium. The origin of this non-ideal magnetohydrodynamic…

Solar and Stellar Astrophysics · Physics 2015-06-05 B. P. Pandey , Mark Wardle

We perform a local (short-wavelength) linear stability analysis of an axisymmetric column of magnetized plasma with a nearly toroidal magnetic field and a smooth poloidal velocity shear by perturbing the equations of relativistic…

High Energy Astrophysical Phenomena · Physics 2015-06-05 Krzysztof Nalewajko , Mitchell C. Begelman

The magnetorotational instability (MRI) occurs when a weak magnetic field destabilises a rotating, electrically conducting fluid with inwardly increasing angular velocity. The MRI is essential to astrophysical disk theory where the shear is…

The effect of shear on the growth of large scale magnetic fields in helical turbulence is investigated. The resulting large-scale magnetic field is also helical and continues to evolve, after saturation of the small scale field, on a slow…

Astrophysics · Physics 2007-05-23 A. Bigazzi , A. Brandenburg , K. Subramanian

We present numerical simulations of the growth and saturation of the Kelvin-Helmholtz instability in a compressible fluid layer with and without a weak magnetic field. In the absence of a magnetic field, the instability generates a single…

Astrophysics · Physics 2009-11-13 M. L. Palotti , F. Heitsch , E. G. Zweibel , Y. -M. Huang

We investigate the density-shear instability in Hall-MHD via numerical simulation of the full non-linear problem, in the context of magnetar activity. We confirm the development of the instability of a plane-parallel magnetic field with an…

High Energy Astrophysical Phenomena · Physics 2015-09-03 Konstantinos N. Gourgouliatos , Todor Kondic , Maxim Lyutikov , Rainer Hollerbach

We perform idealised numerical simulations of magnetic buoyancy instabilities in a model of the solar tachocline. We introduce a simplified model of magnetic flux pumping in an upper layer (the convection zone), and study the effects of its…

Solar and Stellar Astrophysics · Physics 2015-06-04 Adrian J. Barker , Lara J. Silvers , Michael R. E. Proctor , Nigel O. Weiss

Stably stratified layers are present in stellar interiors (radiative zones) as well as planetary interiors - recent observations and theoretical studies of the Earth's magnetic field seem to indicate the presence of a thin, stably…

Solar and Stellar Astrophysics · Physics 2019-10-10 J. Philidet , C. Gissinger , F. Lignières , L. Petitdemange

This paper is the first in a series investigating magnetohydrodynamic instabilities that may contribute to angular-momentum transport and magnetic-field evolution in stellar radiative zones. We focus on shear-driven instabilities,…

Solar and Stellar Astrophysics · Physics 2026-02-10 V. Durepaire , L. Petitdemange , K. Belkacem , A. Guseva , L. Manchon , R. Hollerbach , F. Daniel

We have carried out simulations of the nonlinear evolution of the magnetohydrodynamic (MHD) Kelvin-Helmholtz (KH) instability for compressible fluids in $2\frac{1}{2}$-dimensions, extending our previous work by Frank et al (1996) and Jones…

Astrophysics · Physics 2016-08-30 Hyunju Jeong , Dongsu Ryu , T. W. Jones , Adam Frank

The issue of magnetic confinement in magnetic fusion devices is addressed within a purely magnetic approach. Using some Hamiltonian models for the magnetic field lines, the dual impact of low magnetic shear is shown in a unified way. Away…

Plasma Physics · Physics 2011-03-21 Marie-Christine Firpo , Dana Constantinescu

Intermittent large-scale high-shear flows are found to occur frequently and spontaneously in direct numerical simulations of statistically stationary turbulent Boussinesq magnetohydrodynamic (MHD) convection. The energetic steady-state of…

Solar and Stellar Astrophysics · Physics 2013-09-06 J. Pratt , A. Busse , W. -C. Mueller

By numerically solving the equations of rotating magnetohydrodynamics (MHD), the magnetic effect on dynamical tide is studied. It is found that magnetic field has a significant impact not only on the flow structure, i.e. the internal shear…

Solar and Stellar Astrophysics · Physics 2018-02-21 Xing Wei

Electron-scale Kelvin-Helmholtz instabilities (ESKHI) are found in several astrophysical scenarios. Naturally ESKHI is subject to a background magnetic field, but an analytical dispersion relation and an accurate growth rate of ESKHI under…

Plasma Physics · Physics 2025-02-25 Yao Guo , Dong Wu , Jie Zhang
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