Stabilization of subcritical bypass transition in the leading-edge boundary layer by suction

John, Michael O.; Obrist, Dominik; Kleiser, Leonhard (2014). Stabilization of subcritical bypass transition in the leading-edge boundary layer by suction. Journal of Turbulence, 15(11), pp. 795-805. Taylor & Francis 10.1080/14685248.2014.933226

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This work investigates the subcritical spatial transition in the swept Hiemenz boundary layer by means of direct numerical simulations (DNS). A pair of steady co-rotating vortices located at the attachment line is enforced as a primary disturbance leading to streaks which are stable. A small secondary, time-dependent disturbance interacts with these streaks such that instability and breakdown to turbulence may occur. The instability only occurs for a certain band of secondary disturbance frequencies. Positive secondary instability growth rates could be observed for Reynolds numbers as low as , whereas the linear critical Reynolds number is. Uniform wall suction is shown to stabilise this transition mechanism, analogously to results from linear stability theory. The effects of suction on the formation of primary streaks and on the secondary growth rate are decoupled. For streaks of different suction whose amplitude is held constant by adjusting the Reynolds number, the suction is shown to increase the growth rate of the secondary instability. The stabilising influence of wall suction consists in decreasing the streak amplitude only. Depending on the Reynolds number and the suction strength, breakdown may either occur locally and may be convected along the far-field streamlines, or occur globally and cover broad regions in the downstream direction.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > ARTORG Center for Biomedical Engineering Research > ARTORG Center - Cardiovascular Engineering (CVE)

UniBE Contributor:

Obrist, Dominik

Subjects:

500 Science > 510 Mathematics
500 Science > 530 Physics
600 Technology > 620 Engineering

ISSN:

1468-5248

Publisher:

Taylor & Francis

Language:

English

Submitter:

Dominik Obrist

Date Deposited:

12 Jun 2015 10:25

Last Modified:

12 Jun 2015 10:25

Publisher DOI:

10.1080/14685248.2014.933226

URI:

https://boris.unibe.ch/id/eprint/69380

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