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Type: Journal article
Title: Simulation of a Large-Eddy-Break-up Device (LEBU) in a moderate Reynolds number turbulent boundary layer
Author: Chin, C.
Örlü, R.
Monty, J.
Hutchins, N.
Ooi, A.
Schlatter, P.
Citation: Flow, Turbulence and Combustion, 2017; 98(2):445-460
Publisher: Springer Netherlands
Issue Date: 2017
ISSN: 1386-6184
Statement of
Cheng Chin, Ramis Örlü, Jason Monty, Nicholas Hutchins, Andrew Ooi, Philipp Schlatter
Abstract: 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 R e θ ≈ 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 λ+z>1000 independent of streamwise and wall-normal location when compared to the corresponding turbulent boundary layer without LEBU.
Keywords: Boundary layer; Large eddy simulation; wall turbulence; Large-eddy-break-up device; drag reduction
Description: Published online: 11 August 2016
Rights: © Springer Science+Business Media Dordrecht 2016
RMID: 0030065954
DOI: 10.1007/s10494-016-9757-y
Appears in Collections:Mechanical Engineering publications

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