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We study the stability of cylindrical Taylor-Couette flow in the presence of combined axial and azimuthal magnetic fields, and show that adding an azimuthal field profoundly alters the previous results for purely axial fields. For small…

Astrophysics · Physics 2009-11-13 R. Hollerbach , G. Ruediger

We present azimuthal velocity profiles measured in a Taylor-Couette apparatus, which has been used as a model of stellar and planetary accretion disks. The apparatus has a cylinder radius ratio of $\eta = 0.716$, an aspect-ratio of $\Gamma…

Magnetorotational instability (MRI) is one of the fundamental processes in astrophysics, driving angular momentum transport and mass accretion in a wide variety of cosmic objects. Despite much theoretical/numerical and experimental efforts…

Fluid Dynamics · Physics 2017-11-28 G. Mamatsashvili , F. Stefani , A. Guseva , M. Avila

The linear marginal instability of an axisymmetric MHD Taylor-Couette flow of infinite vertical extension is considered. The dependence of the flow stability on magnetic Prandtl number, Pm, and gap-width between rotating cylinders is…

Astrophysics · Physics 2009-11-07 G. Ruediger , D. Shalybkov

Angular momentum transport in accretion discs is often believed to be due to magnetohydrodynamic turbulence mediated by the magnetorotational instability. Despite an abundant literature on the MRI, the parameters governing the saturation…

Solar and Stellar Astrophysics · Physics 2015-07-15 H. Meheut , S. Fromang , G. Lesur , M. Joos , P. -Y. Longaretti

We show, by means of a perturbative weakly nonlinear analysis, that the axisymmetric magneto-rotational instability (MRI) in a magnetic Taylor-Couette (mTC) flow in a thin-gap gives rise, for very small magnetic Prandtl numbers (P_m), to a…

Astrophysics · Physics 2015-05-13 O. Regev

Toroidal magnetic fields subject to the Tayler instability can transport angular momentum. We show that the Maxwell and Reynolds stress of the nonaxisymmetric field pattern depend linearly on the shear in the cylindrical gap geometry.…

Astrophysics · Physics 2009-11-13 M. Gellert , G. Rüdiger

The stability of conducting Taylor-Couette flows under the presence of toroidal magnetic background fields is considered. For strong enough magnetic amplitudes such magnetohydrodynamic flows are unstable against nonaxisymmetric…

Plasma Physics · Physics 2020-01-08 G. Rüdiger , M. Schultz

The nonaxisymmetric Tayler instability of toroidal magnetic fields due to axial electric currents is studied for conducting incompressible fluids between two coaxial cylinders without endplates. The inner cylinder is considered as so thin…

Solar and Stellar Astrophysics · Physics 2015-05-20 G. Ruediger , M. Schultz , M. Gellert

We investigate magnetic Taylor--Couette flow in the presence of an imposed axial magnetic field. First we calculate nonlinear steady axisymmetric solutions and determine how their strength depends on the applied magnetic field. Then we…

Astrophysics · Physics 2009-11-07 Ashley P. Willis , Carlo F. Barenghi

Global axisymmetric stability of viscous, resistive, magnetized Couette flow is re-examined, with the emphasis on flows that would be hydrodynamically stable according to Rayleigh's criterion: opposing gradients of angular velocity and…

Astrophysics · Physics 2009-11-06 Jeremy Goodman , Hantao Ji

It is demonstrated that the azimuthal magnetorotational instability (AMRI) also works with radially increasing rotation rates contrary to the standard magnetorotational instability for axial fields which requires negative shear. The…

Fluid Dynamics · Physics 2017-12-14 Guenther Rüdiger , Manfred Schultz , Marcus Gellert , Frank Stefani

It is known that in a hydrodynamic Taylor-Couette system uniform rotation or a rotation law with positive shear ('super-rotation') are linearly stable. It is also known that a conducting fluid under the presence of a sufficiently strong…

Solar and Stellar Astrophysics · Physics 2016-02-17 G. Rüdiger , M. Schultz , M. Gellert , F. Stefani

We study the saturation near threshold of the axisymmetric magnetorotational instability (MRI) of a viscous, resistive, incompressible fluid in a thin-gap Taylor-Couette configuration. A vertical magnetic field, Keplerian shear and no-slip,…

Astrophysics · Physics 2009-11-13 O. M. Umurhan , O. Regev , K. Menou

We show by means of a perturbative weakly nonlinear analysis that the axisymmetric magnetorotational instability (MRI) of a viscous, resistive, incompressible rotating shear flow in a thin channel gives rise to a real Ginzburg-Landau…

Astrophysics · Physics 2008-11-26 O. M. Umurhan , K. Menou , O. Regev

This paper presents the analysis of axisymmetric helical magnetorotational instability (HMRI) in the inviscid limit, which is relevant for astrophysical conditions. The inductionless approximation defined by zero magnetic Prandtl number is…

Fluid Dynamics · Physics 2011-12-20 Jānis Priede

Hollerbach and Rudiger have reported a new type of magnetorotational instability (MRI) in magnetized Taylor-Couette flow in the presence of combined axial and azimuthal magnetic fields. The salient advantage of this "helical'' MRI (HMRI) is…

Astrophysics · Physics 2008-11-26 Wei Liu , Jeremy Goodman , Isom Herron , Hantao Ji

The linear marginal instability of an axisymmetric MHD Taylor-Couette flow of infinite vertical extension is considered. For flows with a resting outer cylinder there is a well-known characteristic Reynolds number even without magnetic…

Astrophysics · Physics 2016-08-16 G. Rüdiger , D. A. Shalybkov

We study the stability of cylindrical Taylor-Couette flow in the presence of azimuthal magnetic fields, and show that one obtains non-axisymmetric magnetorotational instabilities, having azimuthal wavenumber m=1. For Omega_o/Omega_i only…

Fluid Dynamics · Physics 2010-01-28 Rainer Hollerbach , Vijaya Teeluck , Gunther Rudiger

Magnetorotational instability (MRI) is the most likely mechanism driving angular momentum transport in astrophysical disks. However, despite many efforts, a conclusive experimental evidence of MRI is still missing. Recently, performing 1D…

Fluid Dynamics · Physics 2023-07-31 A. Mishra , G. Mamatsashvili , F. Stefani