2005/03/31 by Stanislav Boldyrev · 18 citations
Physics and Astronomy · #Anisotropy #Astrophysics and Star Formation Studies #Energy cascade #Fluctuation spectrum #Ionosphere and magnetosphere dynamics #Magnetic energy #Magnetic field #Magnetohydrodynamic drive #Magnetohydrodynamic turbulence #Magnetohydrodynamics #Scaling #Solar and Space Plasma Dynamics #Turbulence #astro-ph #nlin.CD #physics.flu-dyn #physics.plasm-ph
paper · pdf · doi:10.1086/431649
published as Astrophys.J. 626 (2005) L37 · 10 pages, 1 figure; minor changes to match published version
openalex publication_date 2005/05/19 · arxiv created 2005/06/17 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We propose a phenomenological model for incompressible magnetohydrodynamic turbulence. We argue that nonlinear-wave interaction weakens as the energy cascade proceeds to small scales; however, the anisotropy of fluctuations along the large-scale magnetic field increases, which makes turbulence strong at all scales. To explain the weakening of the interaction, we propose that small-scale fluctuations of the velocity and magnetic fields become increasingly dynamically aligned as their scale decreases, so that turbulent "eddies" become locally anisotropic in the plane perpendicular to the large-scale magnetic field. In the limit of weak anisotropy, that is, weak large-scale magnetic field, our model reproduces the Goldreich-Sridhar spectrum, while the limit of strong anisotropy, that is, strong large-scale magnetic field, corresponds to the Iroshnikov-Kraichnan scaling of the spectrum. This is in good agreement with recent numerical results.