Anisotropic three‐dimensional MHD turbulence

Matthaeus, W. H.; Ghosh, S.; Oughton, Sean; Roberts, D. A.

doi:10.1029/95ja03830

Cited by 230 publications

(210 citation statements)

References 27 publications

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“…This includes observations associated with solar energetic particle (SEP) events [74]. Theory and simulation support this claim [78][79][80][81] and several theories of inertial range dynamics build on the idea [55,68,82]. We should note that when the analysis of Bieber et al [74] is applied to the observations of Belcher & Davis [3] the conclusion is that those fluctuations are also dominated by an abundance of perpendicular wave vectors.…”

Section: Heatingmentioning

confidence: 94%

Third-moment descriptions of the interplanetary turbulent cascade, intermittency and back transfer

Coburn

Forman

Smith

et al. 2015

Phil. Trans. R. Soc. A.

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One contribution of 11 to a theme issue 'Dissipation and heating in solar wind turbulence' . We review some aspects of solar wind turbulence with an emphasis on the ability of the turbulence to account for the observed heating of the solar wind. Particular attention is paid to the use of structure functions in computing energy cascade rates and their general agreement with the measured thermal proton heating. We then examine the use of 1 h data samples that are comparable in length to the correlation length for the fluctuations to obtain insights into local inertial range dynamics and find evidence for intermittency in the computed energy cascade rates. When the magnetic energy dominates the kinetic energy, there is evidence of anti-correlation in the cascade of energy associated with the outward-and inward-propagating components that we can only partially explain.

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Section: Heatingmentioning

confidence: 94%

Third-moment descriptions of the interplanetary turbulent cascade, intermittency and back transfer

Coburn

Forman

Smith

et al. 2015

Phil. Trans. R. Soc. A.

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“…To explore this toroidal/poloidal anisotropy further, we present new results from a set of decaying compressible (polytropic) three-dimensional MHD turbulence simulations (see [119] for the equations solved). A periodic pseudospectral method with a resolution of 512 Fourier modes in each Cartesian direction was employed.…”

Section: Component (Variance) Anisotropymentioning

confidence: 99%

Anisotropy in solar wind plasma turbulence

Oughton

Matthaeus

Wan

et al. 2015

Phil. Trans. R. Soc. A.

123

113

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One contribution of 11 to a theme issue 'Dissipation and heating in solar wind turbulence' . A review of spectral anisotropy and variance anisotropy for solar wind fluctuations is given, with the discussion covering inertial range and dissipation range scales. For the inertial range, theory, simulations and observations are more or less in accord, in that fluctuation energy is found to be primarily in modes with quasi-perpendicular wavevectors (relative to a suitably defined mean magnetic field), and also that most of the fluctuation energy is in the vector components transverse to the mean field. Energy transfer in the parallel direction and the energy levels in the parallel components are both relatively weak. In the dissipation range, observations indicate that variance anisotropy tends to decrease towards isotropic levels as the electron gyroradius is approached; spectral anisotropy results are mixed. Evidence for and against wave interpretations and turbulence interpretations of these features will be discussed. We also present new simulation results concerning evolution of variance anisotropy for different classes of initial conditions, each with typical background solar wind parameters.

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“…Such excess magnetic energy has been seen in many other simulations (Pouquet et al 1976;Pouquet and Patterson 1978;Shebalin et al 1983;Matthaeus and Lamkin 1986;Oughton et al 1994;Matthaeus et al 1996), and is also a robust feature in the solar wind, where observations indicate that σ D ≈ − 1 3 Roberts et al 1987a,b). One typically finds that in the solar wind, E/B 2 0 ≈ 1, which in our units corresponds roughly to simulations with B 0 = 1.…”

Section: Spectral Evolutionmentioning

confidence: 87%

“…The fact that the smaller scales are less Alfvénic suggests that these scales are the most quasi-2D-like, and thus the most anisotropic, as is also indicated by the results of the next section. Simulations using initial conditions with no significant initial H k display the same behaviour (Oughton 1994;Matthaeus et al 1996). On the other hand, on comparing runs with increasing values of B 0 (e.g.…”

Section: Spectral Evolutionmentioning

confidence: 89%

“…Observational, simulation, and modelling support for the quality of this approximation is well documented (see e.g. Tu and Marsch 1995;Matthaeus et al 1996Matthaeus et al , 1998Matthaeus et al , 1999. Thus, the incompressible results presented below are also likely to be of relevance to various compressible space physics and astrophysical systems.…”

Section: Governing Equations and Definitionsmentioning

confidence: 91%

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Kinetic helicity and MHD turbulence

Oughton

Prandi

2000

J. Plasma Phys.

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Abstract. The issue of dynamical anisotropy in helical three-dimensional magnetohydrodynamic turbulence with a mean magnetic field B 0 is investigated. Using high-resolution direct numerical simulations, we follow the evolution of various isotropic initial states characterized by their different values of the kinetic helicity. The cross helicity and magnetic helicity of the initial conditions are also varied. In agreement with earlier work, we find that such initial states become anisotropic in of order an eddy-turnover time, with correlation lengths parallel to B 0 remaining largely unchanged while finer scales are excited in the perpendicular directions. Moreover, it is found that the development of both the anisotropy and the energy are essentially independent of the initial level of kinetic helicity. The physics associated with this latter feature is discussed.

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Anisotropic three‐dimensional MHD turbulence

Cited by 230 publications

References 27 publications

Third-moment descriptions of the interplanetary turbulent cascade, intermittency and back transfer

Third-moment descriptions of the interplanetary turbulent cascade, intermittency and back transfer

Anisotropy in solar wind plasma turbulence

Kinetic helicity and MHD turbulence

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