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On least-order flow representations for aerodynamics and aeroacoustics

Schlegel, Michael and Noack, Bernd R. and Jordan, Peter and Dillmann, Andreas and Gröschel, Elmar and Schröder, Wolfgang and Wei, Mingjun and Freund, Jonathan B. and Lehmann, Oliver and Tadmor, Gilead (2012) On least-order flow representations for aerodynamics and aeroacoustics. Journal of Fluid Mechanics, Vol. 697, pp. 367-398. Cambridge University Press. DOI: 10.1017/jfm.2012.70.

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Official URL: http://journals.cambridge.org/action/displayIssue?iid=8527965#


We propose a generalization of proper orthogonal decomposition (POD) for optimal flow resolution of linearly related observables. This Galerkin expansion, termed ‘observable inferred decomposition’ (OID), addresses a need in aerodynamic and aeroacoustic applications by identifying the modes contributing most to these observables. Thus, OID constitutes a building block for physical understanding, leastbiased conditional sampling, state estimation and control design. From a continuum of OID versions, two variants are tailored for purposes of observer and control design, respectively. Firstly, the most probable flow state consistent with the observable is constructed by a ‘least-residual’ variant. This version constitutes a simple, easily generalizable reconstruction of the most probable hydrodynamic state to preprocess efficient observer design. Secondly, the ‘least-energetic’ variant identifies modes with the largest gain for the observable. This version is a building block for Lyapunov control design. The efficient dimension reduction of OID as compared to POD is demonstrated for several shear flows. In particular, three aerodynamic and aeroacoustic goal functionals are studied: (i) lift and drag fluctuation of a two-dimensional cylinder wake flow; (ii) aeroacoustic density fluctuations measured by a sensor array and emitted from a two-dimensional compressible mixing layer; and (iii) aeroacoustic pressure monitored by a sensor array and emitted from a three-dimensional compressible jet. The most ‘drag-related’, ‘lift-related’ and ‘loud’ structures are distilled and interpreted in terms of known physical processes.

Document Type:Article
Additional Information:published online 16 March 2012
Title:On least-order flow representations for aerodynamics and aeroacoustics
AuthorsInstitution or Email of Authors
Schlegel, MichaelTU Berlin, D-10623 Berlin, Germany
Noack, Bernd R.CNRS–Universit´e de Poitiers–ENSMA,F-86036 Poitiers CEDEX, France
Jordan, PeterCNRS–Universit´e de Poitiers–ENSMA, F-86036 Poitiers CEDEX, France
Dillmann, AndreasUNSPECIFIED
Gröschel, ElmarRheinisch-Westfälische Technische Hochschule Aachen, D-52062 Aachen, Germany;ABB Turbo Systems AG, 5400 Baden, Switzerland
Schröder, WolfgangRheinisch-Westfälische Technische Hochschule Aachen, D-52062 Aachen, Germany
Wei, MingjunNew Mexico State University, Las Cruces, NM 88003-8001, USA
Freund, Jonathan B.University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
Lehmann, OliverNortheastern University,Boston, MA 02115, USA
Tadmor, GileadNortheastern University, Boston, MA 02115, USA
Journal or Publication Title:Journal of Fluid Mechanics
Refereed publication:Yes
In Open Access:No
In ISI Web of Science:Yes
Volume:Vol. 697
Page Range:pp. 367-398
Publisher:Cambridge University Press
Keywords:aeroacoustics, low-dimensional models, wakes/jets
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Aircraft Research
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Flight Physics
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Leitungsbereich AS GO
Deposited By: Ilka Micknaus
Deposited On:20 Apr 2012 13:24
Last Modified:26 Mar 2013 13:38

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