Hairpin vortices in turbulent boundary layers
Eitel-Amor G, Flores O, Schlatter P (2014)
Publication Type: Conference contribution
Publication year: 2014
Publisher: Institute of Physics Publishing
Book Volume: 506
Conference Proceedings Title: Journal of Physics: Conference Series
Event location: ESP
DOI: 10.1088/1742-6596/506/1/012008
Abstract
The present work addresses the question whether hairpin vortices are a dominant feature of near-wall turbulence and which role they play during transition. First, the parent-offspring mechanism is investigated in temporal simulations of a single hairpin vortex introduced in a mean shear flow corresponding to turbulent channels and boundary layers up to Reτ 590. Using an eddy viscosity computed from resolved simulations, the effect of a turbulent background is also considered. Tracking the vortical structure downstream, it is found that secondary hairpins are created shortly after initialization. Thereafter, all rotational structures decay, whereas this effect is enforced in the presence of an eddy viscosity. In a second approach, a laminar boundary layer is tripped to transition by insertion of a regular pattern of hairpins by means of defined volumetric forces representing an ejection event. The idea is to create a synthetic turbulent boundary layer dominated by hairpin-like vortices. The flow for Reτ < 250 is analysed with respect to the lifetime of individual hairpin-like vortices. Both the temporal and spatial simulations demonstrate that the regeneration process is rather short-lived and may not sustain once a turbulent background has formed. From the transitional flow simulations, it is conjectured that the forest of hairpins reported in former DNS studies is an outer layer phenomenon not being connected to the onset of near-wall turbulence. © Published under licence by IOP Publishing Ltd.
Authors with CRIS profile
Involved external institutions
Royal Institute of Technology / Kungliga Tekniska Högskolan (KTH)
Sweden (SE)
Universidad Carlos III de Madrid (UC3M)
Spain (ES)
Sweden (SE)
Universidad Carlos III de Madrid (UC3M)
Spain (ES)
How to cite
APA:
Eitel-Amor, G., Flores, O., & Schlatter, P. (2014). Hairpin vortices in turbulent boundary layers. In Journal of Physics: Conference Series. ESP: Institute of Physics Publishing.
MLA:
Eitel-Amor, G., Oscar Flores, and Philipp Schlatter. "Hairpin vortices in turbulent boundary layers." Proceedings of the 1st Multiflow Summer Workshop, ESP Institute of Physics Publishing, 2014.
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