# 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 Müller^{1} and Roland Grappin^{2} — ^{1}Max-Planck-Institut für Plasmaphysik — ^{2}LUTH, 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.