Kinetic helicity and MHD turbulence

Oughton, Sean; Prandi, R.

doi:10.1017/s0022377800008424

Cited by 4 publications

(2 citation statements)

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“…Related to this point, the equations of kinetic helicity in HD turbulence and in MHD turbulence are an interesting subject. For these topics, the reader is referred to [43] for the HD case and [44] for the MHD case.…”

Section: Equation Of Continuitymentioning

confidence: 99%

Modeling the turbulent cross-helicity evolution: production, dissipation, and transport rates

Yokoi

2011

Journal of Turbulence

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It has been recognized that the turbulent cross helicity (correlation between the velocity and magnetic-field fluctuations) can play an important role in several magnetohydrodynamic (MHD) plasma phenomena such as the global magnetic-field generation, turbulence suppression, etc. Despite its relevance to the cross-helicity evolution, little attention has been paid to the dissipation rate of the turbulent cross helicity, ε W . In this paper, we consider the model expression for the dissipation rate of the turbulent cross helicity. In addition to the algebraic model, an evolution equation of ε W is proposed on the basis of the statistical analytical theory of inhomogeneous turbulence. A turbulence model with the modeling of ε W is applied to the solar-wind turbulence. Numerical results on the large-scale evolution of the cross helicity is compared with the satellite observations. It is shown that, as far as the solar-wind application is concerned, the simplest possible algebraic model for ε W is sufficient for elucidating the large-scale spatial evolution of the solar-wind turbulence. Dependence of the cross-helicity evolution on the large-scale velocity structures such as velocity shear and flow expansion is also discussed.

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Section: Equation Of Continuitymentioning

confidence: 99%

Modeling the turbulent cross-helicity evolution: production, dissipation, and transport rates

Yokoi

2011

Journal of Turbulence

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“…The invariants of 3D MHD are the total energy (velocity and magnetic field), the magnetic and cross helicity (see [14,28]). Although the kinetic helicity is a rugged invariant for 3D Euler flows, it is not one for MHD systems, but still an important quantity (see [39]). The magnetic helicity is not conserved when a mean magnetic field is present, see e.g.…”

Section: Introductionmentioning

confidence: 99%

Large eddy simulation for turbulent magnetohydrodynamic flows

Labovsky

Trenchea

2011

Journal of Mathematical Analysis and Applications

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We investigate the mathematical properties of a model for the simulation of large eddies in turbulent, electrically conducting, viscous, incompressible flows. We prove existence and uniqueness of solutions for the simplest (zeroth) closed MHD model (1.7), we show that its solutions converge to the solution of the MHD equations as the averaging radii converge to zero, and derive a bound on the modeling error. Furthermore, we show that the model preserves the properties of the 3D MHD equations: the kinetic energy and the magnetic helicity are conserved, while the cross helicity is approximately conserved and converges to the cross helicity of the MHD equations, and the model is proven to preserve the Alfvén waves, with the velocity converging to that of the MHD, as δ 1 , δ 2 tend to zero. We perform computational tests that verify the accuracy of the method and compare the conserved quantities of the model to those of the averaged MHD.

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