Observation of a Free-Shercliff-Layer Instability in Cylindrical Geometry

Roach, A.; Spence, E. J.; Gissinger, Christophe; Edlund, E.; Sloboda, P.; Goodman, Jeremy; Ji, Hantao

doi:10.1103/physrevlett.108.154502

Cited by 41 publications

(42 citation statements)

References 26 publications

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“…In that respect, notions such as fast and slow waves [20], or Alfvénic MRI, are not relevant in the experimental context. Our analysis is in line with the conclusions of Gissinger et al [22] and Roach et al [23], who relate the modes observed in the Maryland and…”

Section: Discussionsupporting

confidence: 93%

Magneto–Coriolis waves in a spherical Couette flow experiment

Schmitt¹,

Cardin²,

Rizza³

et al. 2013

European Journal of Mechanics - B/Fluids

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The dynamics of fluctuations in a fast rotating spherical Couette flow experiment in the presence of a strong dipolar magnetic field is investigated in detail, through a thorough analysis of the experimental data as well as a numerical study. Fluctuations within the conducting fluid (liquid sodium) are characterized by the presence of several oscillation modes, identified as magneto-Coriolis (MC) modes, with definite symmetry and azimuthal number. A numerical simulation provides eigensolutions which exhibit oscillation frequencies and magnetic signature comparable to the observation. The main characteristics of these hydromagnetic modes is that the magnetic contribution has a fundamental influence on the dynamical properties through the Lorentz forces, although its importance remains weak in an energetical point of view. Another specificity is that the Lorentz forces are confined near the inner sphere where the dipolar magnetic field is the strongest, while the Coriolis forces are concentrated in the outer fluid volume close to the outer sphere.

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Section: Discussionsupporting

confidence: 93%

Magneto–Coriolis waves in a spherical Couette flow experiment

Schmitt¹,

Cardin²,

Rizza³

et al. 2013

European Journal of Mechanics - B/Fluids

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“…Some experiments aimed at reproducing certain features of the accretion disks have focused on Taylor-Couette flows in water or liquid metal, both magnetized and unmagnetized, as the main experimental platform to study disk turbulence and MRI (Ji et al 2006;Roach et al 2012). Gas and plasma experiments are much less numerous and, generally, are not specifically conceived to study the physics of accretion disks (Ji 2011).…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulations of Z-Pinch Experiments to Create Supersonic Differentially Rotating Plasma Flows

Bocchi

Ummels

Chittenden

et al. 2013

ApJ

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The physics of accretion disks is of fundamental importance for understanding of a wide variety of astrophysical sources that includes protostars, X-ray binaries, and active galactic nuclei. The interplay between hydrodynamic flows and magnetic fields and the potential for turbulence-producing instabilities is a topic of active research that would benefit from the support of dedicated experimental studies. Such efforts are in their infancy, but in an effort to push the enterprise forward we propose an experimental configuration which employs a modified cylindrical wire array Z-pinch to produce a rotating plasma flow relevant to accretion disks. We present three-dimensional resistive magnetohydrodynamic simulations which show how this approach can be implemented. In the simulations, a rotating plasma cylinder or ring is formed, with typical rotation velocity ∼30 km s −1 , Mach number ∼4, and Reynolds number in excess of 10 7 . The plasma is also differentially rotating. Implementation of different external magnetic field configurations is discussed. It is found that a modest uniform vertical field of 1 T can affect the dynamics of the system and could be used to study magnetic field entrainment and amplification through differential rotation. A dipolar field potentially relevant to the study of accretion columns is also considered.

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“…Just as the Coriolis force causes rotating flows to become independent of the ordinate along the axis of rotation, so too can magnetic fields cause flows of electrically conducting fluid to become independent of the ordinate parallel to the direction of the applied field. Such free shear layers, now known as Shercliff layers 19 , have been studied both experimentally [20][21][22] , and numerically 19,[23][24][25] . Like their hydrodynamic cousins, these shear layers are unstable to a Kelvin-Helmholtz-type instability when the amount of shear becomes large relative to the restoring force.…”

Section: Introductionmentioning

confidence: 99%

Free MHD Shear Layers In The Presence Of Rotation And Magnetic Field

Spence¹,

Roach²,

Edlund³

et al. 2012

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We present an experimental and numerical study of hydrodynamic and magnetohydrodynamic free shear layers and their stability. We first examine the experimental measurement of globally unstable hydrodynamic shear layers in the presence of rotation, and their range of instability. These are compared to numerical simulations, which are used to explain the modification of the shear layer and thus the critical Rossby number for stability. Magnetic fields are then applied to these scenarios, and globally unstable magnetohydrodynamic shear layers generated. These too are compared to numerical simulations, showing behavior consistent with the hydrodynamic case and previously reported measurements. a) Electronic mail: ejspence@pppl.gov

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Observation of a Free-Shercliff-Layer Instability in Cylindrical Geometry

Cited by 41 publications

References 26 publications

Magneto–Coriolis waves in a spherical Couette flow experiment

Magneto–Coriolis waves in a spherical Couette flow experiment

Numerical Simulations of Z-Pinch Experiments to Create Supersonic Differentially Rotating Plasma Flows

Free MHD Shear Layers In The Presence Of Rotation And Magnetic Field

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