Transition to turbulence by interaction of free-stream and discrete mode perturbations Durbin, Paul Bose, Rikhi
dc.contributor.department Aerospace Engineering 2018-02-19T01:17:29.000 2020-06-29T22:45:15Z 2020-06-29T22:45:15Z Fri Jan 01 00:00:00 UTC 2016 2016-01-01
dc.description.abstract <p>Mixed mode transition is studied by direct numerical simulation. Low frequency streaks are induced within the boundary layer by free-stream turbulence and an Orr-Sommerfeld discrete mode eigenfunction is introduced at the inlet. Amplitudes are selected such that the interaction of these modes can cause transition. Aside from the highest amplitude of free-stream turbulence, neither disturbance alone is sufficient to cause transition within the flowdomain. Results are classified into three routes to transition, depending upon the 2D Tollmien-Schlichting (TS) mode strength and free-stream turbulence intensity. (1) At low turbulence intensities, secondary instabilities instigate transition. On a strong TS mode, Λ vortices develop, but they are neither H nor K type. The pattern and spanwise size of Λ vortices depend upon the frequency and spanwise width of Klebanoff streaks by which they are generated. (2) When the TS mode amplitude is low, transition is via streak breakdown.The streaks are induced by the free-stream turbulence, but this case differs from conventional bypass transition in the mechanism of inception of turbulent spots. Three dimensional visualizations of the perturbation flow field show growing, helical undulations similar to <em>n</em> = 1 instability modes observed in axisymmetric jets and wakes. (3) At high turbulenceintensities, the flow undergoes bypass transition. The TS wave has a small effect, but its influence is seen at the larger of the two amplitudes studied.</p>
dc.description.comments <p>This article is published as Bose, Rikhi, and Paul A. Durbin. "Transition to turbulence by interaction of free-stream and discrete mode perturbations." Physics of Fluids 28, no. 11 (2016): 114105. <a href="" target="_blank">10.1063/1.4966978</a>. Posted with permission.</p>
dc.format.mimetype application/pdf
dc.identifier archive/
dc.identifier.articleid 1103
dc.identifier.contextkey 10984556
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath aere_pubs/103
dc.language.iso en
dc.source.uri 10.1063/1.4966978
dc.subject.disciplines Aerodynamics and Fluid Mechanics
dc.subject.disciplines Aerospace Engineering
dc.title Transition to turbulence by interaction of free-stream and discrete mode perturbations
dc.type article
dc.type.genre article
dspace.entity.type Publication
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