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Delaying transition to turbulence by a passive mechanism
KTH, School of Engineering Sciences (SCI), Mechanics.ORCID iD: 0000-0002-3251-8328
KTH, School of Engineering Sciences (SCI), Mechanics, Stability, Transition and Control.ORCID iD: 0000-0002-4346-4732
2006 (English)In: Physical Review Letters, ISSN 0031-9007, Vol. 96, no 6Article in journal (Refereed) Published
Abstract [en]

Reducing skin friction is important in nature and in many technological applications. This reduction may be achieved by reducing stresses in turbulent boundary layers, for instance tailoring biomimetic rough skins. Here we take a second approach consisting of keeping the boundary layer laminar as long as possible by forcing small optimal perturbations. Because of the highly non-normal nature of the underlying linearized operator, these perturbations are highly amplified and able to modify the mean velocity profiles at leading order. We report results of wind-tunnel experiments in which we implement this concept by using suitably designed roughness elements placed on the skin to enforce nearly optimal perturbations. We show that by using this passive control technique it is possible to sensibly delay transition to turbulence.

Place, publisher, year, edition, pages
2006. Vol. 96, no 6
Keyword [en]
tollmien-schlichting waves, free-stream turbulence, boundary-layer transition, drag reduction, shear flows, growth, instability, transient, stabilization, stability
URN: urn:nbn:se:kth:diva-15428DOI: 10.1103/PhysRevLett.96.064501ISI: 000235394100034ScopusID: 2-s2.0-33144460051OAI: diva2:333469
QC 20100525Available from: 2010-08-05 Created: 2010-08-05Bibliographically approved

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