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Relaxation processes in a low-order three-dimensional magnetohydrodynamics modelThe time asymptotic behavior of a Galerkin model of 3D magnetohydrodynamics (MHD) has been interpreted using the selective decay and dynamic alignment relaxation theories. A large number of simulations has been performed that scan a parameter space defined by the rugged ideal invariants, including energy, cross helicity, and magnetic helicity. It is concluded that time asymptotic state can be interpreted as a relaxation to minimum energy. A simple decay model, based on absolute equilibrium theory, is found to predict a mapping of initial onto time asymptotic states, and to accurately describe the long time behavior of the runs when magnetic helicity is present. Attention is also given to two processes, operating on time scales shorter than selective decay and dynamic alignment, in which the ratio of kinetic to magnetic energy relaxes to values 0(1). The faster of the two processes takes states initially dominant in magnetic energy to a state of near-equipartition between kinetic and magnetic energy through power law growth of kinetic energy. The other process takes states initially dominant in kinetic energy to the near-equipartitioned state through exponential growth of magnetic energy.
Document ID
19910061949
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Stribling, Troy
(Delaware Univ. Newark, DE, United States)
Matthaeus, William H.
(Bartol Research Institute Newark, DE, United States)
Date Acquired
August 14, 2013
Publication Date
August 1, 1991
Publication Information
Publication: Physics of Fluids B
Volume: 3
Issue: 8 pt
ISSN: 0899-8221
Subject Category
Plasma Physics
Accession Number
91A46572
Funding Number(s)
CONTRACT_GRANT: NGT-50338
CONTRACT_GRANT: NSF ATM-89-13627
Distribution Limits
Public
Copyright
Other

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