Minimal transition thresholds in plane Couette flow
2013 (English)In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 25, no 8, 084103- p.Article in journal (Refereed) Published
Subcritical transition to turbulence requires finite-amplitude perturbations. Using a nonlinear optimisation technique in a periodic computational domain, we identify the perturbations of plane Couette flow transitioning with least initial kinetic energy for Re <= 3000. We suggest a new scaling law E-c = O(Re-2.7) for the energy threshold vs. the Reynolds number, in quantitative agreement with experimental estimates for pipe flow. The route to turbulence associated with such spatially localised perturbations is analysed in detail for Re = 1500. Several known mechanisms are found to occur one after the other: Orr mechanism, oblique wave interaction, lift-up, streak bending, streak breakdown, and spanwise spreading. The phenomenon of streak breakdown is analysed in terms of leading finite-time Lyapunov exponents of the associated edge trajectory.
Place, publisher, year, edition, pages
2013. Vol. 25, no 8, 084103- p.
Parallel Shear Flows, Pipe-Flow, Boundary-Layer, Optimal Perturbations, Channel Flows, 3-Dimensional Perturbations, Optimal Excitation, Turbulence, Stability, Growth
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-129468DOI: 10.1063/1.4817328ISI: 000323946200037ScopusID: 2-s2.0-84883436664OAI: oai:DiVA.org:kth-129468DiVA: diva2:653024
FunderSwedish e‐Science Research Center
QC 201310022013-10-022013-09-302013-10-02Bibliographically approved