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| Titel |
Large-scale instability of a generalized turbulent Kolmogorov flow |
| VerfasserIn |
B. Legras, B. Villone |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 16, no. 4 ; Nr. 16, no. 4 (2009-08-31), S.569-577 |
| Datensatznummer |
250013236
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| Publikation (Nr.) |
 copernicus.org/npg-16-569-2009.pdf |
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| Zusammenfassung |
| We present an analytical study of the large scale instability of a
generalized turbulent Kolmogorov flow, i.e. a periodic shear flow
where the molecular viscosity has been substituted by an eddy
viscosity parameterized with the Clark-Smagorinsky model and where
the external forcing is adapted to maintain the flow against this
dissipation. We employ multiscaling technique assuming a scale
separation between the basic scale of such a generalized
turbulent Kolmogorov flow and the largest scales of the flow. The
main result is that an amplitude equation for the large-scale
secondary flow is obtained which exhibits, like for the standard
Kolmogorov flow, an instability of the negative viscosity type.
We find that the presence of mirror symmetry in the basic flow is
a necessary condition and that further propagative and nonlinear
contribution are produced otherwise. The
result is encouraging for the generic existence of large-scale
instabilities of the negative viscosity type in fully turbulent
flows. |
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