The role of helicity in turbulent MHD flows |
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Authors: | E Golbraikh O G Chkhetiani S S Moiseev |
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Institution: | (1) Center for MHD Studies, Ben Gurion University of the Negev, P.O.B. 653, Beer-Sheva, 84105, Israel;(2) Space Research Institute, Russian Academy of Sciences, 117810 Moscow, Russia |
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Abstract: | We have studied the behavior of a helical homogeneous small-scale MHD turbulent flow under the influence of a weak inhomogeneous
large-scale disturbance. We have shown that turbulent energy redistribution in the presence of nonzero helicity occurs mainly
over large scales. Helicity increases correlation time, leading to the weakening of a direct cascade and to the formation
of steep spectra over small scales, with simultaneous turbulent energy growth over large scales. Furthermore, an expression
for the effective viscosity of the mean flow is derived. It is shown that the magnetic field, in addition to the helicity,
reduces the effective viscosity of the medium. This may be important in the study of MHD flow around obstacles in the presence
of an external magnetic field.
Zh. éksp. Teor. Fiz. 114, 171–181 (July 1998)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. |
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