Two-dimensional state in driven magnetohydrodynamic turbulence
Titre | Two-dimensional state in driven magnetohydrodynamic turbulence |
Type de publication | Journal Article |
Year of Publication | 2011 |
Auteurs | Bigot, B, Galtier, S |
Journal | Physical Review EPhysical Review E |
Volume | 83 |
Date Published | Feb |
ISBN Number | 1539-3755 |
Numéro d'accès | WOS:000287488500003 |
Résumé | The dynamics of the two-dimensional (2D) state in driven three-dimensional (3D) incompressible magnetohydrodynamic turbulence is investigated through high-resolution direct numerical simulations and in the presence of an external magnetic field at various intensities. For such a flow the 2D state (or slow mode) and the 3D modes correspond, respectively, to spectral fluctuations in the plane k(parallel to) = 0 and in the area k(parallel to) > 0. It is shown that if initially the 2D state is set to zero it becomes nonnegligible in few turnover times, particularly when the external magnetic field is strong. The maintenance of a large-scale driving leads to a break for the energy spectra of 3D modes; when the driving is stopped, the previous break is removed and a decay phase emerges with Alfvenic fluctuations. For a strong external magnetic field the energy at large perpendicular scales lies mainly in the 2D state, and in all situations a pinning effect is observed at small scales. |