Anisotropic MHD turbulence

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations

Abstract

The solar wind and the interstellar medium are permeated by large-scale magnetic fields that render magnetohydrodynamic (MHD) turbulence anisotropic. In the weak-turbulence limit in which three-wave interactions dominate, analytical and high-resolution numerical results based on random scattering of shear-Alfvén waves propagating parallel to a large-scale magnetic field, as well as direct simulations demonstrate rigorously an anisotropic energy spectrum that scales as k -2, instead of the famous Iroshnikov-Kraichnan (IK) spectrum of k -3/2 for the isotropic case. Even in the absence of a background magnetic field, anisotropy is found to develop with respect to the local magnetic field, although the energy spectrum is globally isotropic and is found to be consistent with a k -3/2 scaling. It is also found in direct numerical simulations that the energy cascade rate is much closer to IK scaling than a Kolmogorov scaling. Recent observations in the solar wind on cascade rates (as functions of the proton temperature and solar wind speed at 1 AU) seem to support this result [Vasquez et al. 2007].

Original languageEnglish (US)
Title of host publicationTURBULENCE AND NONLINEAR PROCESSES IN ASTROPHYSICAL PLASMAS
Subtitle of host publication6th Annual International Astrophysics Conference
Pages137-143
Number of pages7
DOIs
StatePublished - Nov 27 2007
Externally publishedYes
EventTURBULENCE AND NONLINEAR PROCESSES IN ASTROPHYSICAL PLASMAS: 6th Annual International Astrophysics Conference - Oahu, HI, United States
Duration: Mar 16 2007Mar 22 2007

Publication series

NameAIP Conference Proceedings
Volume932
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

OtherTURBULENCE AND NONLINEAR PROCESSES IN ASTROPHYSICAL PLASMAS: 6th Annual International Astrophysics Conference
CountryUnited States
CityOahu, HI
Period3/16/073/22/07

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Keywords

  • Energy cascade
  • Interstellar medium
  • Magnetohydrodynamic turbulence
  • Solar wind

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  • Cite this

    Ng, C. S., & Bhattacharjee, A. (2007). Anisotropic MHD turbulence. In TURBULENCE AND NONLINEAR PROCESSES IN ASTROPHYSICAL PLASMAS: 6th Annual International Astrophysics Conference (pp. 137-143). (AIP Conference Proceedings; Vol. 932). https://doi.org/10.1063/1.2778956