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Simulation of a Large-Eddy-Break-up Device (LEBU) in a Moderate Reynolds Number Turbulent Boundary Layer
KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.ORCID iD: 0000-0002-1663-3553
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2016 (English)In: Flow Turbulence and Combustion, ISSN 1386-6184, E-ISSN 1573-1987, 1-16 p.Article in journal (Refereed) Published
Abstract [en]

A well-resolved large eddy simulation (LES) of a large-eddy break-up (LEBU) device in a spatially evolving turbulent boundary layer is performed with, Reynolds number, based on free-stream velocity and momentum-loss thickness, of Reθ ≈ 4300. The implementation of the LEBU is via an immersed boundary method. The LEBU is positioned at a wall-normal distance of 0.8 δ (δ denoting the local boundary layer thickness at the location of the LEBU) from the wall. The LEBU acts to delay the growth of the turbulent boundary layer and produces global skin friction reduction beyond 180δ downstream of the LEBU, with a peak local skin friction reduction of approximately 12 %. However, no net drag reduction is found when accounting for the device drag of the LEBU in accordance with the towing tank experiments by Sahlin et al. (Phys. Fluids 31, 2814, 1988). Further investigation is performed on the interactions of high and low momentum bulges with the LEBU and the corresponding output is analysed, showing a ‘break-up’ of these large momentum bulges downstream of the LEBU. In addition, results from the spanwise energy spectra show consistent reduction in energy at spanwise length scales for (Formula presented.) independent of streamwise and wall-normal location when compared to the corresponding turbulent boundary layer without LEBU.

Place, publisher, year, edition, pages
Springer, 2016. 1-16 p.
Keyword [en]
Boundary layer, Drag reduction, Large eddy simulation, Large-eddy-break-up device, Wall turbulence, Boundary layer flow, Boundary layers, Computational fluid dynamics, Drag, Friction, Momentum, Reynolds number, Skin friction, Turbulence, Turbulent flow, Boundary layer thickness, Free-stream velocity, Immersed boundary methods, Large eddy, Moderate Reynolds numbers, Skin friction reduction, Turbulent boundary layers, Atmospheric thermodynamics
National Category
Fluid Mechanics and Acoustics
URN: urn:nbn:se:kth:diva-194962DOI: 10.1007/s10494-016-9757-yScopusID: 2-s2.0-84981283791OAI: diva2:1048859

QC 20161122

Available from: 2016-11-22 Created: 2016-11-01 Last updated: 2016-11-22Bibliographically approved

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