Bypass transition and spot nucleation in boundary layers
2016 (English)Manuscript (preprint) (Other academic)
The spatio-temporal aspects of the transition to turbulence are considered in the case of a boundary-layer flow developing above a flat plate exposed to free-stream turbulence. Combining results on the receptivity to free-stream turbulence with the nonlinear concept of a transition threshold, a physically motivated model suggests a spatial distribution of spot nucleation events. To describe the evolution of turbulent spots a probabilistic cellular automaton is introduced, with all parameters directly fitted from numerical simulations of the boundary layer. The nucleation rates are then combined with the cellular automaton model, yielding excellent quantitative agreement with the statistical characteristics for different free-stream turbulence levels. We thus show how the recent theoretical progress on transitional wall-bounded flows can be extended to the much wider class of spatially developing boundary-layer flows.
Place, publisher, year, edition, pages
boundary layers, bypass transition, free-stream turbulence, edge of chaos, cellular automaton
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:kth:diva-186034OAI: oai:DiVA.org:kth-186034DiVA: diva2:924992
QS 2016052016-04-292016-04-292016-05-31Bibliographically approved