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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

The degree of intermittency of the magnetic field of a large-scale dynamo is considered. Based on simulations it is argued that there is a tendency for the field to become more diffuse and non-intermittent as the dynamo saturates. The…

Solar and Stellar Astrophysics · Physics 2011-07-14 Axel Brandenburg

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

It was shown previously that the current-carrying state of a Field Effect Transistor with asymmetric source and drain boundary conditions may become unstable against spontaneous generation of plasma waves [1]. By extending the analysis to…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 M. I. Dyakonov

We investigate the stability to nonaxisymmetric perturbations of an accretion disc in which a poloidal magnetic field provides part of the radial support against gravity. Interchange instability due to radial gradients in the magnetic field…

Astrophysics · Physics 2015-06-24 H. C. Spruit , R. Stehle , J. C. B. Papaloizou

The two-stream instability is a common instability, responsible for many observed phenomena in nature, especially the interaction of jets of various origin with the background plasma (e.g. extragalactic jet interacting with the cosmic…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Miroslav Horky , Petr Kulhanek

The interacting vorticity wave formalism for shear flow instabilities is extended here to the magnetohydrodynamic (MHD) setting, to provide a mechanistic description for the stabilising and destabilising of shear instabilities by the…

Fluid Dynamics · Physics 2015-11-30 Eyal Heifetz , Julian Mak , Jonas Nycander , Orkan M. Umurhan

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 turbulent magnetic diffusivity tensor is determined in the presence of rotation or shear. The question is addressed whether dynamo action from the shear-current effect can explain large-scale magnetic field generation found in…

Astrophysics · Physics 2010-11-05 A. Brandenburg , K. -H. Rädler , M. Rheinhardt , P. J. Käpylä

Using complementary numerical approaches at high resolution, we study the late-time behaviour of an inviscid, incompressible two-dimensional flow on the surface of a sphere. Starting from a random initial vorticity field comprised of a…

Fluid Dynamics · Physics 2015-12-08 David G. Dritschel , Wanming Qi , J. B. Marston

Numerical and observational evidence indicates that, in regions where mixed-layer instability is active, the surface geostrophic velocity is largely induced by surface buoyancy anomalies. Yet, in these regions, the observed surface kinetic…

Atmospheric and Oceanic Physics · Physics 2022-08-01 Houssam Yassin , Stephen M. Griffies

It is shown that ambipolar diffusion as a toy nonlinearity leads to very similar behaviour of large scale turbulent dynamos as full MHD. This is demonstrated using both direct simulations in a periodic box and a closure model for the…

Astrophysics · Physics 2007-05-23 Axel Brandenburg , Kandaswamy Subramanian

We consider a two-dimensional complex plasma layer containing charged dust particles in a perpendicular magnetic field. Computer simulations of both one-component and binary systems are used to explore the equilibrium particle dynamics in…

Plasma Physics · Physics 2014-03-03 T. Ott , H. Löwen , M. Bonitz

We consider the dynamics of a layer of an incompressible electrically conducting fluid interacting with the magnetic field in a two-dimensional horizontally periodic setting. The upper boundary is in contact with the atmosphere, and the…

Analysis of PDEs · Mathematics 2021-01-13 Yanjin Wang , Zhouping Xin

The question of the origin and evolution of magnetic fields in stars possessing a radiative envelope, like the A-type stars, is still regarded as a challenge for stellar physics. Those zones are likely to be differentially rotating, which…

Solar and Stellar Astrophysics · Physics 2015-06-23 Laurène Jouve , Thomas Gastine , François Lignières

The non-linear Hall term present in the induction equation in the electron-magneto-hydrodynamics limit is responsible for the Hall drift of the magnetic field and, in some cases, for the so-called Hall instability. We investigate whether or…

Solar and Stellar Astrophysics · Physics 2012-03-28 Jose A. Pons , Ulrich Geppert

This study examines the stability of a flexible material interface between two fluids of the same viscosity in interaction with a free surface. When the layers are motionless, we provide evidence for the onset of a novel instability by…

Fluid Dynamics · Physics 2024-11-05 Joris Labarbe

We analyse the stability of a magnetized medium consisting of a neutral fluid and a fluid of charged particles, coupled to each other through a drag force and exposed to differential body forces (for example, as the result of radiation…

Astrophysics · Physics 2009-11-07 P. V. Tytarenko , R. J. R. Williams , S. A. E. G. Falle

By employing a local two-fluid theory, we investigate an obliquely propagating electromagnetic instability in the lower hybrid frequency range driven by cross-field current or relative drifts between electrons and ions. The theory…

Astrophysics · Physics 2007-05-23 Hantao Ji , Russell Kulsrud , William Fox , Masaaki Yamada

Lakes and many other geophysical flows are shallow, density stratified, and contain a free-surface. Conventional studies on stratified shear instabilities make Boussinesq approximation. Free-surface arising due to large density variations…

Fluid Dynamics · Physics 2016-10-27 Mihir H. Shete , Anirban Guha