Delaying transition to turbulence by a passive mechanism

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 lo...

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Bibliographic Details
Published in:Physical review letters 2006-02, Vol.96 (6), p.064501-064501, Article 064501
Main Authors: Fransson, Jens H M, Talamelli, Alessandro, Brandt, Luca, Cossu, Carlo
Format: Article
Language:English
Subjects:
boundary-layer transition
drag reduction
Engineering Sciences
Fluid Dynamics
Fluid mechanics
Fluids mechanics
free-stream turbulence
growth
instability
Mechanics
Physics
shear flows
stability
stabilization
tollmien-schlichting waves
transient
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Summary: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.
ISSN:0031-9007
1079-7114
1079-7114
DOI:10.1103/physrevlett.96.064501