Magnetic Helicity Conservation and Inverse Energy Cascade in Electron Magnetohydrodynamic Wave Packets

We study the helicity density patterns which can result from the emerging bipolar regions. Using the relevant dynamo model and the magnetic helicity conservation law we find that the helicity density patterns around the bipolar regions depend on the configuration of the ambient large-scale magnetic field, and in general they show a quadrupole distribution. The position of this pattern relative to the equator can depend on the tilt of the bipolar region. We compute the time–latitude diagrams of the helicity density evolution. The longitudinally averaged effect of the bipolar regions shows two bands of sign for the density distributions in each hemisphere. Similar helicity density patterns are provided by the helicity density flux from the emerging bipolar regions subjected to surface differential rotation.

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Observation of the inverse energy cascade in the modified Korteweg-de Vries equation

EPL (Europhysics Letters) ◽

10.1209/0295-5075/107/14001 ◽

2014 ◽

Vol 107 (1) ◽

pp. 14001 ◽

Cited By ~ 5

Author(s):

D. Dutykh ◽

E. Tobisch

Keyword(s):

Vries Equation ◽

Energy Cascade ◽

Inverse Energy Cascade ◽

De Vries

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Implications of Magnetic Helicity Conservation

Magnetic Helicity in Space and Laboratory Plasmas - Geophysical Monograph Series ◽

10.1029/gm111p0011 ◽

2013 ◽

pp. 11-16 ◽

Cited By ~ 1

Author(s):

Allen H. Boozer

Keyword(s):

Magnetic Helicity ◽

Helicity Conservation

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Ocean Eddy Energetics in the Spectral Space as Revealed by High-Resolution General Circulation Models

Journal of Physical Oceanography ◽

10.1175/jpo-d-19-0034.1 ◽

2019 ◽

Vol 49 (11) ◽

pp. 2815-2827

Author(s):

Shengpeng Wang ◽

Zhao Jing ◽

Qiuying Zhang ◽

Ping Chang ◽

Zhaohui Chen ◽

...

Keyword(s):

Energy Conversion ◽

General Circulation ◽

Surface Wind ◽

Circulation Model ◽

General Circulation Models ◽

Ocean General Circulation Model ◽

Energy Cascade ◽

Spectral Space ◽

Inverse Energy Cascade ◽

Barotropic Energy Conversion

AbstractIn this study, the global eddy kinetic energy (EKE) budget in horizontal wavenumber space is analyzed based on 1/10° ocean general circulation model simulations. In both the tropical and midlatitude regions, the barotropic energy conversion from background flow to eddies is positive throughout the wavenumber space and generally peaks at the scale (Le) where EKE reaches its maximum. The baroclinic energy conversion is more pronounced at midlatitudes. It exhibits a dipolar structure with positive and negative values at scales smaller and larger than Le, respectively. Surface wind power on geostrophic flow results in a significant EKE loss around Le but deposits energy at larger scales. The interior viscous dissipation and bottom drag inferred from the pressure flux convergence act as EKE sink terms. The latter is most efficient at Le while the former is more dominant at smaller scales. There is an evident mismatch between EKE generation and dissipation in the spectral space especially at the midlatitudes. This is reconciled by a dominant forward energy cascade on the equator and a dominant inverse energy cascade at the midlatitudes.

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Inverse Energy Cascade in Advanced MHD Turbulence (the RNG Method)

Symposium - International Astronomical Union ◽

10.1017/s0074180900174248 ◽

1993 ◽

Vol 157 ◽

pp. 255-261

Author(s):

N. Kleeorin ◽

I. Rogachevskii

Keyword(s):

Magnetic Field ◽

Large Scale ◽

Magnetic Field Effect ◽

Magnetic Reynolds Number ◽

Energy Cascade ◽

Small Scale ◽

Magnetic Fluctuations ◽

Mhd Turbulence ◽

Inverse Energy Cascade ◽

Large Scale Magnetic Field

The nonlinear (in terms of the large-scale magnetic field) effect of the modification of the magnetic force by an advanced small-scale magnetohydrodynamic (MHD) turbulence is considered. The phenomenon is due to the generation of magnetic fluctuations at the expense of hydrodynamic pulsations. It results in a decrease of the elasticity of the large-scale magnetic field.The renormalization group (RNG) method was employed for the investigation of the MHD turbulence at the large magnetic Reynolds number. It was found that the level of the magnetic fluctuations can exceed that obtained from the equipartition assumption due to the inverse energy cascade in advanced MHD turbulence.This effect can excite an instability of the large-scale magnetic field due to the energy transfer from the small-scale turbulent pulsations. This instability is an example of the inverse energy cascade in advanced MHD turbulence. It may act as a mechanism for the large-scale magnetic ropes formation in the solar convective zone and spiral galaxies.

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Infrared Reynolds number dependency of the two-dimensional inverse energy cascade

Journal of Fluid Mechanics ◽

10.1017/s0022112010005628 ◽

2011 ◽

Vol 667 ◽

pp. 463-473 ◽

Cited By ~ 15

Author(s):

ANDREAS VALLGREN

Keyword(s):

Reynolds Number ◽

Cascade Range ◽

Energy Cascade ◽

Energy Spectra ◽

Small Scale ◽

Two Dimensional ◽

Inverse Energy Cascade ◽

Linear Friction ◽

Non Local ◽

Reynolds Number Dependency

High-resolution simulations of forced two-dimensional turbulence reveal that the inverse cascade range is sensitive to an infrared Reynolds number, Reα = kf/kα, where kf is the forcing wavenumber and kα is a frictional wavenumber based on linear friction. In the limit of high Reα, the classic k−5/3 scaling is lost and we obtain steeper energy spectra. The sensitivity is traced to the formation of vortices in the inverse energy cascade range. Thus, it is hypothesized that the dual limit Reα → ∞ and Reν = kd/kf → ∞, where kd is the small-scale dissipation wavenumber, will lead to a steeper energy spectrum than k−5/3 in the inverse energy cascade range. It is also found that the inverse energy cascade is maintained by non-local triad interactions.

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