Edge states as mediators of bypass transition in boundary-layer flows
2016 (English)In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645Article in journal (Refereed) Submitted
The concept of edge state is investigated in the asymptotic suction boundary layer in relation with the receptivity process to noisy perturbations and the nucleation of turbulent spots. Edge tracking is first performed numerically, without imposing any discrete symmetry, in a large computational domain allowing for full spatial localisation of the perturbation velocity. The edge state is a three-dimensional localised structure recurrently characterised by a single low-speed streak that experiences erratic bursts and planar shifts. This recurrent streaky structure is then compared with predecessors of individual spot nucleation events, triggered by non-localised initial noise. The present results suggest a nonlinear picture, rooted in dynamical systems theory, of the nucleation process of turbulent spots in boundary-layer flows, in which the localised edge states play the role of state-space mediator.
Place, publisher, year, edition, pages
boundary layers, transition to turbulence, nonlinear dynamical systems
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:kth:diva-185958OAI: oai:DiVA.org:kth-185958DiVA: diva2:924986
QS 2016052016-04-292016-04-292016-05-10Bibliographically approved