Optimal growth, model reduction and control in a separated boundary-layer flow using global eigenmodes
2007 (English)In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 579, 305-314 p.Article in journal (Refereed) Published
Two-dimensional global eigenmodes are used as a projection basis both for analysing the dynamics and building a reduced model for control in a prototype separated boundary-layer flow. In the present configuration, a high aspect ratio smooth cavity-like geometry confines the separation bubble. Optimal growth analysis using the reduced basis shows that the sum of the highly non-normal global eigenmodes are able to describe a localized disturbance. Subject to this worst-case initial condition, a large transient growth associated with the development of a wavepacket along the shear layer followed by a global cycle related to the two unstable global eigenmodes is found. The flow simulation procedure is coupled to a measurement feedback controller, which senses the wall shear stress at the downstream lip of the cavity and actuates at the upstream lip. A reduced model for the control optimization is obtained by a projection on the least stable global eigenmodes, and the resulting linear-quadratic-gaussian controller is applied to the Navier--Stokes time integration. It is shown that the controller is able to damp out the global oscillations.
Place, publisher, year, edition, pages
2007. Vol. 579, 305-314 p.
Boundary layer flow, Eigenvalues and eigenfunctions, Feedback control, Flow control, Mathematical models, Optimization, Shear stress, Control optimization, Flow simulation, Global eigenmodes
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:kth:diva-9543DOI: 10.1017/S0022112007005496ISI: 000247023600011ScopusID: 2-s2.0-34548175491OAI: oai:DiVA.org:kth-9543DiVA: diva2:117425
QC 201009232008-11-132008-11-122010-09-23Bibliographically approved