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Frequency selection by feedback control in a turbulent shear flow

  • Many previous studies have shown that the turbulent mixing layer under periodic forcing tends to adopt a lock-on state, where the major portion of the fluctuations in the flow are synchronized at the forcing frequency. The goal of this experimental study is to apply closed-loop control in order to provoke the lock-on state, using information from the flow itself. We aim to determine the range of frequencies for which the closed-loop control can establish the lock-on, and what mechanisms are contributing to the selection of a feedback frequency. In order to expand the solution space for optimal closed-loop control laws, we use the genetic programming control (CPC) framework. The best closed-loop control laws obtained by CPC are analysed along with the associated physical mechanisms in the mixing layer flow. The resulting closed-loop control significantly outperforms open-loop forcing in terms of robustness to changes in the free-stream velocities. In addition, the selection of feedback frequencies is not locked to the most amplifiedMany previous studies have shown that the turbulent mixing layer under periodic forcing tends to adopt a lock-on state, where the major portion of the fluctuations in the flow are synchronized at the forcing frequency. The goal of this experimental study is to apply closed-loop control in order to provoke the lock-on state, using information from the flow itself. We aim to determine the range of frequencies for which the closed-loop control can establish the lock-on, and what mechanisms are contributing to the selection of a feedback frequency. In order to expand the solution space for optimal closed-loop control laws, we use the genetic programming control (CPC) framework. The best closed-loop control laws obtained by CPC are analysed along with the associated physical mechanisms in the mixing layer flow. The resulting closed-loop control significantly outperforms open-loop forcing in terms of robustness to changes in the free-stream velocities. In addition, the selection of feedback frequencies is not locked to the most amplified local mode, but rather a range of frequencies around it.show moreshow less

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Metadaten
Author details:Vladimir Parezanović, Laurent Cordier, Andreas Spohn, Thomas Duriez, Bernd R. Noack, Jean-Paul Bonnet, Marc Segond, Markus AbelORCiDGND, Steven L. Brunton
URN:urn:nbn:de:kobv:517-opus4-413693
DOI:https://doi.org/10.25932/publishup-41369
ISSN:1866-8372
Title of parent work (English):Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
Publication series (Volume number):Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe (572)
Publication type:Postprint
Language:English
Date of first publication:2019/02/05
Publication year:2016
Publishing institution:Universität Potsdam
Release date:2019/02/05
Tag:free shear layers; instability control; turbulence control
Issue:572
Number of pages:37
Source:Journal of Fluid Mechanics 797 (2016), pp. 247-283 DOI 10.1017/jfm.2016.261
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät
DDC classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Peer review:Referiert
Publishing method:Open Access
Grantor:Cambridge University Press (CUP)
License (German):License LogoKeine öffentliche Lizenz: Unter Urheberrechtsschutz
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