Diffusion and dispersion of passive tracers: Navier-Stokes vs. MHD turbulence

Busse, A. and Mueller, W.-C. (2007) Diffusion and dispersion of passive tracers: Navier-Stokes vs. MHD turbulence. Europhysics Letters, 78(1), p. 14003. (doi: 10.1209/0295-5075/78/14003)

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A comparison of turbulent diffusion and pair-dispersion in homogeneous, macroscopically isotropic Navier-Stokes (NS) and nonhelical magnetohydrodynamic (MHD) turbulence based on high-resolution direct numerical simulations is presented. Significant differences between MHD and NS systems are observed in the pair-dispersion properties, in particular a strong reduction of the separation velocity in MHD turbulence as compared to the NS case. It is shown that in MHD turbulence the average pair-dispersion is slowed down for τd  t  10τd, τd being the Kolmogorov time, due to the alignment of the relative Lagrangian tracer velocity with the local magnetic field. Significant differences in turbulent single-particle diffusion in NS and MHD turbulence are not detected. The fluid particle trajectories in the vicinity of the smallest dissipative structures are found to be characteristically different although these comparably rare events have a negligible influence on the statistics investigated in this work.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Busse, Dr Angela
Authors: Busse, A., and Mueller, W.-C.
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
Journal Name:Europhysics Letters
Publisher:EDP Sciences
ISSN (Online):1286-4854

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