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dc.contributor.author
Rorai, C.
dc.contributor.author
Rosenberg, Duane
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Pouquet, Annick
dc.contributor.author
Mininni, Pablo Daniel
dc.date.available
2015-06-09T13:58:13Z
dc.date.issued
2013-06-12
dc.identifier.citation
Rorai, C.; Rosenberg, D.; Pouquet, A.; Mininni, Pablo Daniel; Helicity dynamics in stratified turbulence in the absence of forcing; Amer Physical Soc; Physical Review E; 87; 6; 6-2013; 0630070(13);
dc.identifier.issn
1539-3755
dc.identifier.uri
http://hdl.handle.net/11336/641
dc.description.abstract
A numerical study of decaying stably stratified flows is performed. Relatively high stratification (Froude number ≈10 −2 - 10 −1 ) and moderate Reynolds (Re) numbers (Re≈ 3 -6 ×10 3) are considered and a particular emphasis is placed on the role of helicity (velocity-vorticity correlations), which is not an invariant of the nondissipative equations. The problem is tackled by integrating the Boussinesq equations in a periodic cubical domain using different initial conditions: a nonhelical Taylor-Green (TG) flow, a fully helical Beltrami [Arnold-Beltrami-Childress (ABC)] flow, and random flows with a tunable helicity. We show that for stratified ABC flows helicity undergoes a substantially slower decay than for unstratified ABC flows. This fact is likely associated to the combined effect of stratification and large-scale coherent structures. Indeed, when the latter are missing, as in random flows, helicity is rapidly destroyed by the onset of gravitational waves. A type of large-scale dissipative "cyclostrophic" balance can be invoked to explain this behavior. No production of helicity is observed, contrary to the case of rotating and stratified flows. When helicity survives in the system, it strongly affects the temporal energy decay and the energy distribution among Fourier modes. We discover in fact that the decay rate of energy for stratified helical flows is much slower than for stratified nonhelical flows and can be considered with a phenomenological model in a way similar to what is done for unstratified rotating flows. We also show that helicity, when strong, has a measurable effect on the Fourier spectra, in particular at scales larger than the buoyancy scale, for which it displays a rather flat scaling associated with vertical shear, as observed in the planetary boundary layer.
dc.format
application/pdf
dc.language.iso
eng
dc.publisher
Amer Physical Soc
dc.rights
info:eu-repo/semantics/openAccess
dc.rights.uri
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.subject
Stratification
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Turbulence
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Helicity
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Ciencias Naturales y Exactas
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Ciencias Físicas
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Física de Los Fluidos y Plasma
dc.title
Helicity dynamics in stratified turbulence in the absence of forcing
dc.type
info:eu-repo/semantics/article
dc.type
info:ar-repo/semantics/artículo
dc.type
info:eu-repo/semantics/publishedVersion
dc.date.updated
2016-03-30 10:35:44.97925-03
dc.journal.volume
87
dc.journal.number
6
dc.journal.pagination
0630070(13)
dc.journal.pais
Estados Unidos
dc.journal.ciudad
New York
dc.description.fil
Fil: Rorai, C.. National Center For Atmospheric Research; Estados Unidos de América; ICTP (International Center for Theoretical Physics); Italia;
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Fil: Rosenberg, D.. National Center for Computational Sciences. Oak Ridge National Laboratory; Estados Unidos de América;
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Fil: Pouquet, A.. National Center For Atmospheric Research; Estados Unidos de América; ICTP (International Center for Theoretical Physics); Italia;
dc.description.fil
Fil: Mininni, Pablo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires; Argentina; National Center for Atmospheric Research; Estados Unidos de América;
dc.journal.title
Physical Review E
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/doi/http://dx.doi.org/10.1103/PhysRevE.87.063007
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