THE DECAY OF A WEAK LARGE-SCALE MAGNETIC FIELD IN TWO-DIMENSIONAL TURBULENCE

ABSTRACT We investigate the decay of a large-scale magnetic field in the context of incompressible, two-dimensional magnetohydrodynamic turbulence. It is well established that a very weak mean field, of strength significantly below equipartition value, induces a small-scale field strong enough to in...

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Bibliographic Details
Published in:The Astrophysical journal 2016-06, Vol.823 (2), p.111-111
Main Authors: Kondi, Todor, Hughes, David W., Tobias, Steven M.
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COMPARATIVE EVALUATIONS
Computational fluid dynamics
COMPUTERIZED SIMULATION
DECAY
DIFFUSION
Diffusivity
Fluid flow
FLUIDS
MAGNETIC FIELDS
MAGNETIC REYNOLDS NUMBER
MAGNETOHYDRODYNAMICS
magnetohydrodynamics (MHD)
MEAN-FIELD THEORY
Reynolds number
TURBULENCE
Turbulent flow
TWO-DIMENSIONAL CALCULATIONS
VISIBLE RADIATION
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Summary:ABSTRACT We investigate the decay of a large-scale magnetic field in the context of incompressible, two-dimensional magnetohydrodynamic turbulence. It is well established that a very weak mean field, of strength significantly below equipartition value, induces a small-scale field strong enough to inhibit the process of turbulent magnetic diffusion. In light of ever-increasing computer power, we revisit this problem to investigate fluids and magnetic Reynolds numbers that were previously inaccessible. Furthermore, by exploiting the relation between the turbulent diffusion of the magnetic potential and that of the magnetic field, we are able to calculate the turbulent magnetic diffusivity extremely accurately through the imposition of a uniform mean magnetic field. We confirm the strong dependence of the turbulent diffusivity on the product of the magnetic Reynolds number and the energy of the large-scale magnetic field. We compare our findings with various theoretical descriptions of this process.
ISSN:0004-637X
1538-4357
DOI:10.3847/0004-637X/823/2/111