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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

We analyse numerically the linear stability of a liquid metal flow in a rectangular duct with perfectly electrically conducting walls subject to a uniform transverse magnetic field. A non-standard three dimensional vector stream…

Fluid Dynamics · Physics 2012-09-26 Jānis Priede , Svetlana Aleksandrova , Sergei Molokov

The magnetorotational instability (MRI) is considered to be one of the most powerful sources of turbulence in hydrodynamically stable quasi-Keplerian flows, such as those governing accretion disk flows. Although the linear stability of…

Fluid Dynamics · Physics 2017-11-21 A. Guseva , R. Hollerbach , A. P. Willis , M. Avila

We study the magneto-rotational instability of an incompressible flow which rotates with angular velocity Omega(r)=a+b/r^2 where r is the radius and $a$ and b are constants. We find that an applied magnetic field destabilises the flow, in…

Astrophysics · Physics 2008-11-26 Ashley P. Willis , Carlo F. Barenghi

We study the magnetorotational instability in cylindrical Taylor-Couette flow, with the (vertically unbounded) cylinders taken to be perfect conductors, and with externally imposed spiral magnetic fields. The azimuthal component of this…

Astrophysics · Physics 2009-11-11 G. Ruediger , R. Hollerbach , M. Schultz , D. A. Shalybkov

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

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

The MHD flow driven by a travelling magnetic field (TMF) in an annular channel is investigated numerically. For sufficiently large magnetic Reynolds number Rm, or if a large enough pressure gradient is externally applied, the system…

Fluid Dynamics · Physics 2016-03-23 Christophe Gissinger , Paola Rodriguez-Imazio , Stephan Fauve

The nonaxisymmetric 'kink-type' Tayler instability (TI) of toroidal magnetic fields is studied for conducting incompressible fluids of uniform density between two infinitely long cylinders rotating around the same axis. It is shown that for…

Solar and Stellar Astrophysics · Physics 2015-05-13 G. Ruediger , M. Schultz

The linear stability of MHD Taylor-Couette flows in axially unbounded cylinders is considered, for magnetic Prandtl number unity. Magnetic fields varying from purely axial to purely azimuthal are imposed, with a general helical field…

Solar and Stellar Astrophysics · Physics 2015-05-14 G. Ruediger , M. Gellert , M. Schultz , R. Hollerbach

All experiments, which have been proposed so far to model the magnetorotational instability (MRI) in the laboratory, involve a Couette flow of liquid metals in a rotating annulus. All liquid metals have small magnetic Prandtl numbers, Pm,…

Astrophysics · Physics 2009-11-10 Koichi Noguchi , Vladimir I. Pariev

The magnetorotational instability (MRI) is thought to be a powerful source of turbulence and momentum transport in astrophysical accretion discs, but obtaining observational evidence of its operation is challenging. Recently, laboratory…

Fluid Dynamics · Physics 2015-09-15 A. Guseva , A. P. Willis , R. Hollerbach , M. Avila

This study is concerned with numerical linear stability analysis of liquid metal flow in a square duct with thin electrically conducting walls subject to a uniform transverse magnetic field. We derive an asymptotic solution for the base…

Fluid Dynamics · Physics 2016-01-27 Jānis Priede , Thomas Arlt , Leo Bühler

We reveal and investigate a new type of linear axisymmetric helical magnetorotational instability which is capable of destabilizing viscous and resistive rotational flows with radially increasing angular velocity, or positive shear. This…

Fluid Dynamics · Physics 2019-10-23 G. Mamatsashvili , F. Stefani , R. Hollerbach , G. Rüdiger

We analyse numerically the linear stability of the fully developed flow of a liquid metal in a rectangular duct subject to a transverse magnetic field. The walls of the duct perpendicular to the magnetic field are perfectly conducting…

Fluid Dynamics · Physics 2015-05-13 J. Priede , S. Aleksandrova , S. Molokov

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…

Fluid Dynamics · Physics 2015-10-28 Adam Child , Evy Kersalé , Rainer Hollerbach

We investigate the nonlinear dynamics of turbulent shear flows, with and without rotation, in the context of a simple but physically motivated closure of the equation governing the evolution of the Reynolds stress tensor. We show that the…

Astrophysics · Physics 2009-11-10 Pascale Garaud , Gordon I. Ogilvie

The magnetorotational instability (MRI) is thought to be a powerful source of turbulence in Keplerian accretion disks. Motivated by recent laboratory experiments, we study the MRI driven by an azimuthal magnetic field in an electrically…

Solar and Stellar Astrophysics · Physics 2017-11-21 Anna Guseva , Ashley P. Willis , Rainer Hollerbach , Marc Avila

We study magnetic Taylor-Couette flow in a system having nondimensional radii $r_i=1$ and $r_o=2$, and periodic in the axial direction with wavelengths $h\ge100$. The rotation ratio of the inner and outer cylinders is adjusted to be…

Fluid Dynamics · Physics 2017-06-07 Rainer Hollerbach , Nigel Sibanda , Eun-jin Kim

We study the Rayleigh-Taylor problem for two incompressible, immiscible, viscous magnetohydrodynamic (MHD) flows, with zero resistivity, surface tension (or without surface tenstion) and special initial magnetic field, evolving with a free…

General Mathematics · Mathematics 2012-05-02 Fei Jiang , Song Jiang , Yanjin Wang