Numerical study of the primary instability in a separated boundary layer transition under elevated free-stream turbulence
Journal article
Authors | Langari, Mostafa and Yang, Zhiyin |
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Abstract | Numerical studies of laminar-to-turbulent transition in a separation bubble subjected to two free-stream turbulence levels (FST) have been performed using Large-Eddy Simulation (LES). Separation of the laminar boundary layer occurs at a curvature change over a plate with a semi-circular leading edge at Re = 3450 based on the plate thickness and the uniform inlet velocity. A numerical trip is used to produce the targeted free-stream turbulence levels and the decay of free-stream turbulence is well predicted. A dynamic sub-grid-scale model is employed in the current study and a good agreement has been obtained between the LES results and the experimental data. Detailed analysis of the LES data has been carried out to investigate the primary instability mechanism. The flow visualisations and spectral analysis of the separated shear layer reveal that the 2D Kelvin-Helmholtz instability mode, well known to occur at low FST levels, is bypassed at higher levels leading to earlier breakdown to turbulence. |
Keywords | Instability; Separated boundary layer |
Year | 2013 |
Journal | Physics of Fluids |
Publisher | AIP Publishing |
ISSN | 10706631 |
Digital Object Identifier (DOI) | https://doi.org/10.1063/1.4816291 |
Web address (URL) | http://hdl.handle.net/10545/620640 |
hdl:10545/620640 | |
Publication dates | 25 Jul 2013 |
Publication process dates | |
Deposited | 17 Oct 2016, 19:48 |
Rights | Archived with thanks to Physics of Fluids |
Contributors | University of Sussex, Brighton, UK and University of Derby, UK |
File | File Access Level Open |
File | File Access Level Open |
https://repository.derby.ac.uk/item/94z99/numerical-study-of-the-primary-instability-in-a-separated-boundary-layer-transition-under-elevated-free-stream-turbulence
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