Mixed mode transition to turbulence in boundary layers

Bose, Rikhi

doi:10.31274/etd-180810-5509

Cited by 1 publication

(3 citation statements)

References 61 publications

(176 reference statements)

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“…This leads to relatively rapidly growing, 2-dimensional, instability waves. Bose (2016) showed that the same three regimes -Λ vortices, helices and undulatory breakdown -occur as the free-stream turbulence level increases, but now the instability waves arise naturally. Evidence of these behaviors can be seen in simulations and experiments (Brinkerhoff and Yaras 2015;Hack and Zaki 2014;Lardeau et al 2012;Nagarajan et al 2007;Walker and Gostelow 1989).…”

Section: Mixed Mode Transitionmentioning

confidence: 96%

“…The wave can be seen in the plan form, too, but the cross-span contours are broken up because they are superimposed on streaks. A recent study of mixed mode transition in zero and adverse pressure gradients delineated a range of behaviors (Bose 2016;Bose and Durbin 2016a,b). The observations are empirical, obtained through direct numerical simulation (DNS ).…”

Section: Mixed Mode Transitionmentioning

confidence: 99%

“…Inflectional instability waves have a phase speed similar to the inner modes. Bose and Durbin (2016a) and Bose (2016) investigated the same Falkner-Skan case as Hack and Zaki (2014). With no, or low, inlet turbulence, two-dimensional instability waves arose spontaneouslyas is commonly seen in simulations with strong adverse pressure gradient or flow separation.…”

Section: Streak Instabilities In Boundary Layersmentioning

confidence: 99%

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Perspectives on the Phenomenology and Modeling of Boundary Layer Transition

Durbin

2017

Flow Turbulence Combust

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This article is a perspective review of boundary layer transition. Both orderly and bypass transition are discussed, but with a decided emphasis on bypass routes. The focus is on transition in a natural, perturbed environment. Then orderly transition occurs through Λ vortices, that develop locally on instability waves. The precursors to bypass transition are boundary layer 'streaks'. Transition proceeds through inner and outer mode secondary instability, leading to patches of turbulence: in zero pressure gradient, bypass transition develops through local, undulatory, outer mode breakdown; in sufficiently adverse pressure gradient, bypass transition proceeds through inner mode instability, which may be of varicose or of helical form.Phenomenology of the creation, growth and breakdown of streaks is surveyed. Theories of shear sheltering, transient and optimal growth, and Orr-Sommerfeld continuous mode resonance are summarized.Recent developments in predictive modeling are summarized. These include laminar fluctuation, and intermittency models.Some open questions are discussed, as are needs for further research.

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