Vortex disruption by magnetohydrodynamic feedback

Mak, Julian; Griffiths, Sue; Hughes, David W.

doi:10.1103/physrevfluids.2.113701

Cited by 22 publications

(21 citation statements)

References 52 publications

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“…This is as a result of the formation of alternating vortices on either side of the thread and leads to structures that are visually similar to those observed. Once the instability is sufficiently evolved, currents build up as a consequence of the bending of the magnetic field, which ultimately results in the magnetic field reconnecting and destroying the undulations (Mak et al 2017). This physical process reproduces the key features of the observed dynamics.…”

Section: Simulationsmentioning

confidence: 99%

Observations of the Kelvin–Helmholtz Instability Driven by Dynamic Motions in a Solar Prominence

Hillier

Polito

2018

ApJL

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Prominences are incredibly dynamic across the whole range of their observable spatial scales, with observations revealing gravity-driven fluid instabilities, waves, and turbulence. With all these complex motions, it would be expected that instabilities driven by shear in the internal fluid motions would develop. However, evidence of these have been lacking. Here we present the discovery in a prominence, using observations from the Interface Region Imaging Spectrograph (IRIS), of a shear flow instability, the Kelvin-Helmholtz sinusoidal-mode of a fluid channel, driven by flows in the prominence body. This finding presents a new mechanism through which we can create turbulent motions from the flows observed in quiescent prominences. The observation of this instability in a prominence highlights their great value as a laboratory for understanding the complex interplay between magnetic fields and fluid flows that play a crucial role in a vast range of astrophysical systems.

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Section: Simulationsmentioning

confidence: 99%

Observations of the Kelvin–Helmholtz Instability Driven by Dynamic Motions in a Solar Prominence

Hillier

Polito

2018

ApJL

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“…Note there are two stable ranges with positive slope, and one unstable region between, with a negative slope (as for negative resistivity). This im- plies that barrier formation is a transport bifurcation, which occurs when local magnetic intensity exceeds the threshold given by (21). This mechanism resembles a transport bifurcation in magnetically confined systems [39,40].…”

Section: Analysis: Localmentioning

confidence: 58%

“…The turbulent or "eddy" resistivity, η T , is ubiquitous in these models (and corresponds to β above). While η T is often taken as kinematic (η T ∼ η K ∼ k ṽ 2 k τ c where τ c is the self-correlation time) for many applications, nonlinear dependence of η T on magnetic field and potential has been observed in numerous simulations [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Such nonlinearity arises from the fact that the magnetic fields alter the turbulent flows which scatter them.…”

Section: Introductionmentioning

confidence: 99%

Spontaneous transport barriers quench turbulent resistivity in two-dimensional magnetohydrodynamics

2019

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This Letter identifies the physical mechanism for the quench of turbulent resistivity in 2D MHD. Without an imposed, ordered magnetic field, a multi-scale, blob-and-barrier structure of magnetic potential forms spontaneously. Magnetic energy is concentrated in thin, linear barriers, located at the interstices between blobs. The barriers quench the transport and kinematic decay of magnetic energy. The local transport bifurcation underlying barrier formation is linked to the inverse cascade of A 2 and negative resistivity, which induce local bistability. For small scale forcing, spontaneous layering of the magnetic potential occurs, with barriers located at the interstices between layers. This structure is effectively a magnetic staircase.

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“…A key point of Z-induced quenching is that only a weak b 0 field is needed at large Rm. The physics underlying quenching can be understood as vortex disruption [13].…”

Section: Introductionmentioning

confidence: 99%

On the role of cross-helicity in $β$-plane magnetohydrodynamic turbulence

Heinonen¹,

Diamond²,

Katz³

et al. 2021

Preprint

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Magnetohydrodynamic (MHD) turbulence on a β-plane with an in-plane mean field, a system which serves as a simple model for the solar tachocline, is investigated analytically and computationally. We show that conservation of squared magnetic potential in this system leads to a global increase in the cross-helicity, which is otherwise conserved in pure MHD (for which the Rossby parameter β is zero). We perform a closure using weak turbulence theory and show that the crosshelicity spectrum entirely determines momentum transport. We also note that perturbation theory for small Rossby parameter is impossible in weak turbulence, since it changes the topology of surfaces on which resonant interactions occur. We support our results with numerical simulations, which clearly indicate that the cross-helicity is most important in the transitional regime between Rossby and Alfvénic turbulence.

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Vortex disruption by magnetohydrodynamic feedback

Cited by 22 publications

References 52 publications

Observations of the Kelvin–Helmholtz Instability Driven by Dynamic Motions in a Solar Prominence

Observations of the Kelvin–Helmholtz Instability Driven by Dynamic Motions in a Solar Prominence

Spontaneous transport barriers quench turbulent resistivity in two-dimensional magnetohydrodynamics

On the role of cross-helicity in $β$-plane magnetohydrodynamic turbulence

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