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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

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

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

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 report the first direct evidence for the axisymmetric standard magnetorotational instability (SMRI) from a combined experimental and numerical study of a magnetized liquid-metal shear flow in a Taylor-Couette cell with independently…

Instrumentation and Methods for Astrophysics · Physics 2022-09-20 Yin Wang , Erik P. Gilson , Fatima Ebrahimi , Jeremy Goodman , Hantao Ji

Simulations of astrophysical disks in the shearing box that are subject to the magnetorotational instability (MRI) show that activity appears to be reduced as the magnetic Prandtl number (Pm) is lowered. On the other hand, calculations for…

Solar and Stellar Astrophysics · Physics 2015-05-18 O. M. Umurhan

The excitation conditions of the magnetorotational instability are studied for axially unbounded Taylor-Couette flows of various gap widths between the cylinders. The cylinders are considered as made from both perfect-conducting or…

Fluid Dynamics · Physics 2023-03-28 G. Rüdiger , M. Schultz

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

Azimuthal magnetorotational instability is a mechanism that generates nonaxisymmetric field pattern. Nonlinear simulations in an infinite Taylor-Couette system with current-free external field show, that not only the linearly unstable mode…

Astrophysics · Physics 2009-11-13 M. Gellert , G. Ruediger , A. Fournier

We study the convective and absolute forms of azimuthal magnetorotational instability (AMRI) in a Taylor-Couette (TC) flow with an imposed azimuthal magnetic field. We show that the domain of the convective AMRI is wider than that of the…

Fluid Dynamics · Physics 2021-08-04 A. Mishra , G. Mamatsashvili , V. Galindo , F. Stefani

In this paper, we investigate numerically the flow of an electrically conducting fluid in a cylindrical Taylor-Couette flow when an axial magnetic field is applied. To minimize Ekman recirculation due to vertical no-slip boundaries, two…

Fluid Dynamics · Physics 2015-06-03 Christophe Gissinger , Jeremy Goodman , Hantao Ji

Despite the importance of the magnetorotational instability (MRI) as a fundamental mechanism for angular momentum transport in magnetized accretion disks, it has yet to be demonstrated in the laboratory. A liquid sodium alpha-omega dynamo…

Astrophysics · Physics 2009-11-07 K. Noguchi , V. I. Pariev , S. A. Colgate , J. Nordhaus , H. F. Beckley

We consider axially periodic Taylor-Couette geometry with insulating boundary conditions. The imposed basic states are so-called Chandrasekhar states, where the azimuthal flow $U_\phi$ and magnetic field $B_\phi$ have the same radial…

Solar and Stellar Astrophysics · Physics 2016-06-01 M. Gellert , G. Rüdiger , M. Schultz , A. Guseva , R. Hollerbach

Magneto-rotational instability (MRI) is an important instability mechanism for rotating flows with magnetic fields. In particular, when the strength of the magnetic field tends to zero, the stability criterion for rotating flows is…

Analysis of PDEs · Mathematics 2024-10-28 Zhiwu Lin , Yucong Wang , Wenpei Wu

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 instability of a quasi-Kepler flow in dissipative Taylor-Couette systems under the presence of an homogeneous axial magnetic field is considered with focus to the excitation of nonaxisymmetric modes and the resulting angular momentum…

Solar and Stellar Astrophysics · Physics 2015-05-30 M. Gellert , G. Rüdiger , M. Schultz

We investigate the stability of differentially rotating proto-neutron stars (PNSs) with a toroidal magnetic field. Stability criteria for nonaxisymmetric MHD instabilities are derived using a local linear analysis. PNSs are expected to have…

Astrophysics · Physics 2009-11-13 Youhei Masada , Takayoshi Sano , Hideaki Takabe

The Global Magnetorotational Instability (MRI) is investigated for a configuration in which the rotation frequency changes only in a narrow transition region. If the vertical wavelength of the unstable mode is of the same order or smaller…

Instrumentation and Methods for Astrophysics · Physics 2011-02-11 J. Pino , S. M. Mahajan

In preparation for an experimental study of magnetorotational instability (MRI) in liquid metal, we present non-ideal two-dimensional magnetohydrodynamic simulations of the nonlinear evolution of MRI in the experimental geometry. The…

Astrophysics · Physics 2009-11-13 Wei Liu , Jeremy Goodman , Hantao Ji

The standard magnetorotational instability (SMRI) is a promising mechanism for turbulence and rapid accretion in astrophysical disks. It is a magnetohydrodynamic (MHD) instability that destabilizes otherwise hydrodynamically stable disk…