Azouzi, Alexandre

Cossu, Carlo

Michelet, Roger

Nicot, Christian

Pier, Benoît

Scott, Julian F.

Siddiqui, Muhammad Ehtisham

Vasudevan, Mukund

HAL-Polytechnique

Transition and control in rotating-disk boundary-layerMuhammad Ehtisham Siddiqui, Benoˆıt Pier, Mukund Vasudevan, Julian F.Scott, Carlo Cossu, Alexandre Azouzi, Christian Nicot, Roger MicheletTo cite this version:Muhammad Ehtisham Siddiqui, Benoˆıt Pier, Mukund Vasudevan, Julian F. Scott, Carlo Cossu,et al.. Transition and control in rotating-disk boundary-layer. Euromech Fluid MechanicsConference 8, Sep 2010, Bad Reichenhall, Germany. <hal-00632327>HAL Id: hal-00632327https://hal.archives-ouvertes.fr/hal-00632327Submitted on 14 Oct 2011HAL is a multi-disciplinary open accessarchive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come fromteaching and research institutions in France orabroad, or from public or private research centers.L’archive ouverte pluridisciplinaire HAL, estdestine´e au de´poˆt et a` la diffusion de documentsscientifiques de niveau recherche, publie´s ou non,e´manant des e´tablissements d’enseignement et derecherche franc¸ais ou e´trangers, des laboratoirespublics ou prive´s.Transition and control in rotating-disk boundary-layerM. E. SIDDIQUI∗, B. PIER∗, MUKUND V.∗, J. SCOTT∗,C. COSSU†, A. AZOUZI∗, C. NICOT∗, R. MICHELET∗The flow due an infinite disk rotating in otherwise still fluid has served as thearchetypical configuration for the study of three-dimensional boundary layers and isknown to display a sharp transition from laminar to turbulent flow at a nondimen-sional critical radius R ≃ 510. Using linear stability analysis, this location was foundby Lingwood1 to precisely coincide with the onset of local absolute instability. Morerecently2, a fully nonlinear analysis and a secondary stability analysis have furthercontributed to the understanding of the complex dynamics prevailing near the tran-sition radius. An open-loop control strategy3 has been theoretically shown4 to beapplicable in this context. The aim is to delay onset of secondary perturbations, andthus transition, by a controlled modification of the primary nonlinear state.The present experimental investigation has been undertaken to confirm these pre-dictions and to test the practical applicability of the control method.The experimental arrangement consists of a 50 cm diameter glass disk that is ro-tated at constant angular speeds, up to 1500 rpm. Control is applied via a set ofneedles, evenly distributed on a cylinder placed above the disk. The forcing parame-ters are adjusted and optimized by changing the number of needles and the rotationrate of the cylinder (which can be varied independently of the disk rotation rate). Asecond technique, using microstructured roughness elements on the disk surface, isalso currently being implemented.The flow features, with and without control, are characterized by time-resolvedlocal hot-wire measurements. The influence of the different control parameters andforcing strategies will be discussed and compared with theoretical predictions.∗Laboratoire de me´canique des fluides et d’acoustique; CNRS—Universite´ de Lyon ; E´cole centralede Lyon ; 36 avenue Guy-de-Collongue ; F-69134 E´cully cedex.†Institut de me´canique des fluides de Toulouse ; CNRS—Universite´ de Toulouse ; alle´e Camille-Soula ; F-31400 Toulouse.1Lingwood, J. Fluid Mech. 299, 17–33 (1995).2Pier, J. Fluid Mech. 487, 315–343 (2003).3Pier, Proc. R. Soc. Lond. A 459, 1105–1115 (2003).4Pier, J. Eng. Math. 57, 237–251 (2007).

Transition and control in rotating-disk boundary-layer

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Transition and control in rotating-disk boundary-layer

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