Diffusion and dispersion in magnetohydrodynamic turbulence:: The influence of mean magnetic fields

The properties of magnetohydrodynamic (MHD) turbulence under the influence of a strong mean magnetic field are investigated from the Lagrangian viewpoint by tracking fluid particles in direct numerical simulations. The particle trajectories show characteristic bends near vortex sheets. A strong mean magnetic field leads to preferential diffusion parallel to the mean magnetic field. The two-particle relative dispersion process shows a dependence on the orientation of the initial separation vector. The relative dispersion is slowed down for initial separation vectors aligned with the mean magnetic field. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.