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dc.contributor.author
 hal.structure.identifier
CHERUBINI, Stefania
134975 Laboratoire de Dynamique des Fluides [DynFluid]
dc.contributor.authorDE TULLIO, Marco
dc.contributor.author
 hal.structure.identifier
DE PALMA, Pietro
19097 Dipartimento di Ingegneria Meccanica e Gestionale [DIMEG]
dc.contributor.authorPASCAZIO, Giuseppe
dc.date.accessioned2014
dc.date.available2014
dc.date.issued2013
dc.date.submitted2014
dc.identifier.issn0022-1120
dc.identifier.urihttp://hdl.handle.net/10985/8973
dc.description.abstractThis work provides a global optimization analysis, looking for perturbations inducing the largest energy growth at a finite time in a boundary-layer flow in the presence of smooth three-dimensional roughness elements. Amplification mechanisms are described which can bypass the asymptotical growth of Tollmien–Schlichting waves. Smooth axisymmetric roughness elements of different height have been studied, at different Reynolds numbers. The results show that even very small roughness elements, inducing only a weak deformation of the base flow, can localize the optimal disturbance characterizing the Blasius boundary-layer flow. Moreover, for large enough bump heights and Reynolds numbers, a strong amplification mechanism has been recovered, inducing an increase of several orders of magnitude of the energy gain with respect to the Blasius case. In particular, the highest value of the energy gain is obtained for an initial varicose perturbation, differently to what found for a streaky parallel flow. Optimal varicose perturbations grow very rapidly by transporting the strong wall-normal shear of the base flow, which is localized in the wake of the bump. Such optimal disturbances are found to lead to transition for initial energies and amplitudes considerably smaller than sinuous optimal ones, inducing hairpin vortices downstream of the roughness element.
dc.language.isoen
dc.publisherCambridge University Press (CUP)
dc.rightsPost-print
dc.subjectboundary layers, boundary layer stability, transition to turbulence
dc.subjectcouche limite, stabilité, transition vers la turbulence
dc.titleTransient growth in the flow past a three-dimensional smooth roughness element
dc.identifier.doi10.1017/jfm.2013.177
dc.typdocArticle dans une revue avec comité de lecture
dc.localisationCentre de Paris
dc.subject.halSciences de l'ingénieur: Mécanique: Mécanique des fluides
ensam.audienceInternationale
ensam.page642-670.
ensam.journalJournal of Fluid Mechanics
ensam.volume724
ensam.languagefr
hal.identifierhal-01086742
hal.version1
hal.statusaccept
dc.identifier.eissn1469-7645


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