Weak Alfvén-wave turbulence revisited.

Phys Rev E Stat Nonlin Soft Matter Phys

Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford OX1 3NP, United Kingdom.

Published: March 2012

AI Article Synopsis

  • The study analyzes weak Alfvénic turbulence as a mixed state of interacting Alfvén waves and 2D condensate, noting a lack of spectral continuity between them.
  • The research finds distinct energy spectra for Alfvén waves and 2D modes, with Alfvén waves being more energetic until a certain wave number indicates the transition to strong turbulence.
  • When the 2D modes are forced, a 2D inverse cascade occurs at larger scales, while weak to strong turbulence transitions happen at smaller scales.

Article Abstract

Weak Alfvénic turbulence in a periodic domain is considered as a mixed state of Alfvén waves interacting with the two-dimensional (2D) condensate. Unlike in standard treatments, no spectral continuity between the two is assumed, and, indeed, none is found. If the 2D modes are not directly forced, k(-2) and k(-1) spectra are found for the Alfvén waves and the 2D modes, respectively, with the latter less energetic than the former. The wave number at which their energies become comparable marks the transition to strong turbulence. For imbalanced energy injection, the spectra are similar, and the Elsasser ratio scales as the ratio of the energy fluxes in the counterpropagating Alfvén waves. If the 2D modes are forced, a 2D inverse cascade dominates the dynamics at the largest scales, but at small enough scales, the same weak and then strong regimes as described above are achieved.

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http://dx.doi.org/10.1103/PhysRevE.85.036406DOI Listing

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