Noise-Sustained Convective Instability in a Magnetized Taylor-Couette Flow

Abstract

The helical magnetorotational instability of the magnetized Taylor-Couette flow is studied numerically in a finite cylinder. A distant upstream insulating boundary is shown to stabilize the convective instability entirely while reducing the growth rate of the absolute instability. The reduction is less severe with larger height. After modeling the boundary conditions properly, the wave patterns observed in the experiment turn out to be a noise-sustained convective instability. After the source of the noise resulted from unstable Ekman and Stewartson layers is switched off, a slowly-decaying inertial oscillation is observed in the simulation. We reach the conclusion that the experiments completed to date have not yet reached the regime of absolute instability.

16 pages, 6 figures and 1 table. submitted to ApJ. minor revision according to the referee

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Cited by in corpus (7)

• Helical magnetorotational instability in a Taylor-Couette flow with strongly reduced Ekman pumping
• Non-axisymmetric Magnetorotational Instabilities in Cylindrical Taylor-Couette Flow
• On the relation of standard and helical magnetorotational instability
• Absolute versus convective helical magnetorotational instability in a Taylor-Couette flow
• Inviscid helical magnetorotational instability in cylindrical Taylor-Couette flow
• Standard and helical magnetorotational instability: How singularities create paradoxal phenomena in MHD
• Liquid metal experiments on the helical magnetorotational instability