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Influence of confinement on a two-dimensional wake

Biancofiore, Luca ; Gallaire, François ; Pasquetti, Richard

In: Journal of Fluid Mechanics, 2011, vol. 688, p. 297-320

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    Titre
    • Influence of confinement on a two-dimensional wake
    Auteur
    • Biancofiore, Luca. Laboratoire J. A. Dieudonné Université de Nice Sophia Antipolis, Parc Valrose, F-06108 Nice CEDEX02, France
    • Gallaire, François. EPFL/LFMI, Route Cantonale, Lausanne, Switzerland
    • Pasquetti, Richard. Laboratoire J. A. Dieudonné Université de Nice Sophia Antipolis, Parc Valrose, F-06108 Nice CEDEX02, France
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Journal of Fluid Mechanics, 2011, vol. 688, p. 297-320. Cambridge University Press
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:295443
    Summary
    The spatio-temporal development of an incompressible two-dimensional viscous wake flow confined by two flat slipping plates is investigated by means of direct numerical simulation (DNS), using a spectral Chebyshev multi-domain method. The limit between unstable and stable configurations is determined with respect to several non-dimensional parameters: the confinement, the velocity ratio and two different Reynolds numbers, $100$ and $500$. The comparison of such limit curves with theoretical results obtained by Juniper (J. Fluid Mech., vol.565, 2006, pp.171-195) confirms the existence of a region at moderate confinement where the instability is maximal. Moreover, instabilities are also observed under sustained co-flow, in the form of a vacillating front. Using a direct computation of the two-dimensional base flow, we perform a local linear stability analysis for several velocity profiles prevailing at different spatial locations, so as to determine the local spatio-temporal nature of the flow: convectively unstable or absolutely unstable. Comparisons of the DNS and local stability analysis results are provided and discussed