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Modal analysis of roughness-induced crossflow vortices in a Falkner-Skan-Cooke boundary layer

Brynjell-Rahkola M, Schlatter P, Hanifi A, Henningson DS (2013)

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Publication Type: Conference contribution

Publication year: 2013

Publisher: TSFP-8

Book Volume: 2

Conference Proceedings Title: International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2013

Event location: Poitiers, FRA

ISBN: 9780000000002

Abstract

A three-dimensional global stability analysis using high-order direct numerical simulations is performed to investigate the effect of surface roughness with Reynolds number (based on roughness height) Rek above and below the critical value for transition, on the eigenmodes of a Falkner-Skan-Cooke boundary layer. The surface roughness is introduced with the immersed boundary method and the eigenvalues and eigenfunctions are solved using an iterative time-stepper method. The study reveals a global instability for the case with higher Reynolds number that causes the flow in the non-linear simulations to break down to turbulence shortly downstream of the roughness. Examination of the unstable linear global modes show that these are the same modes that are observed in experiments immediately before breakdown due to secondary instability, which emphasizes the importance of these modes in transition.

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APA:

Brynjell-Rahkola, M., Schlatter, P., Hanifi, A., & Henningson, D.S. (2013). Modal analysis of roughness-induced crossflow vortices in a Falkner-Skan-Cooke boundary layer. In International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2013. Poitiers, FRA: TSFP-8.

MLA:

Brynjell-Rahkola, Mattias, et al. "Modal analysis of roughness-induced crossflow vortices in a Falkner-Skan-Cooke boundary layer." Proceedings of the 8th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2013, Poitiers, FRA TSFP-8, 2013.

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