Journal
ASTROPHYSICAL JOURNAL
Volume 702, Issue 2, Pages 1190-1198Publisher
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/702/2/1190
Keywords
ISM: kinematics and dynamics; MHD; turbulence
Categories
Funding
- NSF [AST-0808118]
- Center for Magnetic Self-Organization
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We performed a series of high-resolution (up to 1024(3)) direct numerical simulations of hydro and magnetohydrodynamic (MHD) turbulence. Our simulations correspond to the strong MHD turbulence regime that cannot be treated perturbatively. We found that for simulations with normal viscosity the slopes for energy spectra of MHD are similar to ones in hydro, although slightly more shallower. However, for simulations with hyperviscosity the slopes were very different, for instance, the slopes for hydro simulations showed a pronounced and well defined bottleneck effect, while the MHD slopes were relatively much less affected. We believe that this is indicative of MHD strong turbulence being less local than the Kolmogorov turbulence. This calls for revision of MHD strong turbulence models that assume local as-in-hydro case cascading. Nonlocality of MHD turbulence casts doubt on numerical determination of the slopes with currently available (512(3)-1024(3)) numerical resolutions, including simulations with normal viscosity. We also measure various so-called alignment effects and discuss their influence on the turbulent cascade.
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