Bonn 2010 – wissenschaftliches Programm

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EP: Fachverband Extraterrestrische Physik

EP 7: Fundamental Physics

EP 7.3: Vortrag

Dienstag, 16. März 2010, 15:30–15:45, AKM

Surprises in the theory of anisotropic magnetohydrodynamic turbulence — •Wolf-Christian Müller1 and Roland Grappin21Max-Planck-Institut für Plasmaphysik — 2LUTH, Observatoire de Paris

A new approach toward the analysis of high-Reynolds-number direct numerical simulations of incompressible magnetohydrodynamic (MHD) turbulence subject to a strong mean magnetic field has led to unexpected results: the scaling of one dimensional spectra taken along rays passing through the origin of Fourier space is independent of the rays’ orientation with respect to the mean magnetic field direction; the spectral amplitude variation with respect to the angle between a ray and the mean magnetic field can be eliminated by normalization with an angle-dependent dissipation wavenumber. Thus the anisotropy of MHD turbulence permeated by a strong mean magnetic field does not appear as direction dependent scaling but rather as a direction dependent Reynolds number. These findings invalidate most present phenomenologies for macroscopically anisotropic MHD turbulence which are based on the critical balance argument.

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