Self-organisation and non-linear dynamics in driven magnetohydrodynamic turbulent flows

Abstract

Magnetohydrodynamic turbulent flows driven by random mechanical and electromagnetic external forces of zero helicities are investigated by means of direct numerical simulations. It is shown that despite the absence of helicities in the forcing, the system is attracted to self-organized helical states that exhibit laminar behaviour despite the large value of the Reynolds numbers examined. We demonstrate that the correlation time of the external forces is controlling the time spent on these states, i.e. for short correlation times the system remains in the turbulent state while as the correlation time is increased the system spends more and more time in the self-organised states. As a result, time averaged statistics can significantly be affected by the time spent on these states. These results have important theoretical implications for the understanding of the suppression of non-linearities in plasma fusion devises as well as in astrophysical observations.

7 pages, 6 figures

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Cited by in corpus (11)

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• Tridimensional to bidimensional transition in magnetohydrodynamic turbulence with a guide field and kinetic helicity injection
• Large-scale dynamics of magnetic helicity
• Triad interactions and the bidirectional turbulent cascade of magnetic helicity
• Forcing-dependent dynamics and emergence of helicity in rotating turbulence
• Comparison of forcing functions in magnetohydrodynamic turbulence
• Self-organization and transition to turbulence in isotropic fluid motion driven by negative damping at low wavenumbers
• Chaotic behavior of Eulerian MHD turbulence
• Helicity dynamics, inverse and bi-directional cascades in fluid and MHD turbulence: A brief review