Helical turbulence: Turbulent viscosity and instability of the second moments

The evolution of weak large-scale disturbances in the helical turbulence is considered. High-order statistical moments are taken into account in the frames of two-scale analog of Orszag diffusion approximation. The appearance of the instability of second moments is demonstrated for k< α/ ν ( k is...

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Bibliographic Details
Published in:Physica A 1998-09, Vol.258 (1), p.55-68
Main Authors: Belian, A., Chkhetiani, O., Golbraikh, E., Moiseev, S.
Format: Article
Language:English
Subjects:
Helical turbulence
Instability
Viscosity
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Summary:The evolution of weak large-scale disturbances in the helical turbulence is considered. High-order statistical moments are taken into account in the frames of two-scale analog of Orszag diffusion approximation. The appearance of the instability of second moments is demonstrated for k< α/ ν ( k is wave vector, α and ν are proportional to the mean helicity and mean energy viscosity, respectively). Turbulent viscosity diminishing in comparison with the non-helical case is also demonstrated. These phenomenona qualitatively agree with previous results of other authors on the slow-down of energy transfer along the spectrum, from large to small scales at non-zero helicity.
ISSN:0378-4371
1873-2119
DOI:10.1016/S0378-4371(98)00212-X