Alfvén waves and ideal two-dimensional Galerkin truncated magnetohydrodynamics

AMS Citation:
Krstulovic, G., M. -E. Brachet, and A. Pouquet, 2011: Alfvén waves and ideal two-dimensional Galerkin truncated magnetohydrodynamics. Physical Review E, 84, 016410, doi:10.1103/PhysRevE.84.016410.
Date:2011-07-28
Resource Type:article
Title:Alfvén waves and ideal two-dimensional Galerkin truncated magnetohydrodynamics
Abstract: We investigate numerically the dynamics of two-dimensional Euler and ideal magnetohydrodynamics (MHD) flows in systems with a finite number of modes, up to 40962, for which several quadratic invariants are preserved by the truncation and the statistical equilibria are known. Initial conditions are the Orszag-Tang vortex with a neutral X point centered on a stagnation point of the velocity field in the large scales. In MHD, we observe that the total energy spectra at intermediate times and intermediate scales correspond to the interactions of eddies and waves, ET(k)~k-3/2. Moreover, no pseudodissipative range is visible for either Euler or ideal MHD in two dimensions. In the former case, this may be linked to the existence of a vanishing turbulent viscosity whereas in MHD, the numerical resolution employed may be insufficient. When imposing a uniform magnetic field to the flow, we observe a lack of saturation of the formation of small scales together with a significant slowing down of their equilibration, with however a cutoff independent partial thermalization being reached at intermediate scales.
Peer Review:Refereed
Copyright Information:Copyright 2011 American Physical Society.
OpenSky citable URL: ark:/85065/d7tb17dp
Publisher's Version: 10.1103/PhysRevE.84.016410
Author(s):
  • Giorgio Krstulovic
  • Marc-Etienne Brachet
  • Annick Pouquet - NCAR/UCAR
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