Onset of global instability behind distributed surface roughness in a Falkner–Skan–Cooke boundary layer
2015 (English)Report (Other academic)
A three-dimensional linear global stability analysis of a Falkner–Skan–Cooke boundary layer with distributed three-dimensional surface roughness is performed. The Falkner–Skan–Cooke boundary layer models the flow over swept airplane wings, and investigation of the critical roughness size for which a global instability emerges is thus of great importance within aeronautical applications. The study considers high-order direct numerical simulations and shows that such a critical roughness height exists for the Falkner–Skan–Cooke boundary layer. The roughness Reynolds number and roughness element aspect ratio for which this happens is comparable to the transition data reported in the literature for two-dimensional boundary layers. This demonstrates the importance of the local flow conditions in the vicinity of the roughness for triggering a global instability, although the resulting breakdown scenario is completely different from that of two-dimensional boundary layers. This breakdown scenario is studied in detail, and a global energy analysis is used to reveal the structures and mechanisms responsible for production and dissipation of perturbation energy.
Place, publisher, year, edition, pages
2015. , 33 p.
Fluid Mechanics and Acoustics Aerospace Engineering
Research subject Engineering Mechanics; Aerospace Engineering
IdentifiersURN: urn:nbn:se:kth:diva-175347OAI: oai:DiVA.org:kth-175347DiVA: diva2:860446
QC 201510152015-10-122015-10-122015-10-15Bibliographically approved