Coherent structures in the boundary layer of a flat thick plate

B Podvin (1) , Y Fraigneau (1) , C Tenaud (1) , Virginie Daru (1, 2)

1 LIMSI - Laboratoire d'Informatique pour la Mécanique et les Sciences de l'Ingénieur
2 DynFluid - Laboratoire de Dynamique des Fluides

We use POD and EPOD (extended POD) analysis to extract the main features of the flow over a thick flat plate simulated with a LES. Our goal is to better understand the coupling between the velocity field and the surface pressure field. We find that POD modes based on the full velocity and energy fields contain both flapping and shedding frequencies. Pressure modes are found to be uniform in the spanwise direction and the most intense variations take place at the mean reattachment point. Velocity modes educed from the pressure modes with EPOD are seen to correspond to eddies shed by the recirculation bubble. Résumé : Onconsi ere l ecoulementau-dessusd'uneplaqueplanéepaisse.Nousutilisonslasimulationauxgrandeechellesetl'analysePOD/EPODpourcomprendrelecouplageentrelechampdevitesseetlechampdepres-sioalaparoi.LesmodesPODextraitsdelavitessecontiennentdesfréquencescorrespondantauxphénoenesdeflappingetdeshedding.Lesmodesdepressionsontuniformesdansladirectiontransverseetlesvariationslesplusintensessontobservéesaupointderéattachement.Lesmodesdevitesseconstruitapartirdesmodesdepressionavecl'approcheEPODcorrespondenadestourbillonsassociéalabullederecirculation.

Keywords: Mots-clefs:Séparation; POD; Couplagevitesse-pression

Domains: Physics [physics]; Mechanics [physics]; Fluid mechanics [physics.class-ph]; Mathematics [math]; Analysis of PDEs [math.AP]

B Podvin, Y Fraigneau, C Tenaud, Virginie Daru. Coherent structures in the boundary layer of a flat thick plate. Comptes Rendus Mécanique, 2014, 342, pp.417 - 424. ⟨10.1016/j.crme.2014.05.006⟩. ⟨hal-01080643⟩