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| Titel |
Total energy cascade and residual energy in MHD turbulence: homogeneous versus expanding (solar wind) turbulence |
| VerfasserIn |
Roland Grappin, Wolf-Christian Müller, Andrea Verdini |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250104200
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| Publikation (Nr.) |
 EGU/EGU2015-3623.pdf |
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| Zusammenfassung |
| Standard phenomenologies of MHD turbulence generally neglect deviations from
kinetic-magnetic energies equipartition. However, solar wind turbulence commonly
shows a magnetic excess (or positive residual energy) in the inertial range, with a
definite power-law. We report here direct MHD simulation results showing a magnetic
excess, both in homogeneous and expanding turbulence, with the latter taking into
account the radial flow (expanding box model or EBM). We show that the results on
magnetic excess, both scaling laws and amplitude, can be interpreted as resulting
from the competition between the nonlinear stretching of the magnetic field by
the velocity field and the relaxation to equipartition by the linear propagation of
Alfvén waves. We generalize in this way earlier results on homogeneous MHD
turbulence. |
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