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Flow Reversal in Turbulent Boundary Layers with Varying Pressure Gradients

Willert, Christian and Soria, Julio and Cuvier, Christophe and Foucaut, Jean Marc and Laval, Jean Philippe (2018) Flow Reversal in Turbulent Boundary Layers with Varying Pressure Gradients. 19th International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics, 16.-19. Jul. 2018, Lisbon, Portugal.

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Official URL: http://www.lisbon-lasersymposium.org/lxlaser2018

Abstract

This contribution describes detailed PIV measurements obtained in turbulent boundary layers in an effort to capture rarely occurring flow reversals within the viscous sublayer, which have been observed in both experiments and direct numerical simulations. Due to their confinement to the viscous sublayer along with their rare occurrence on the order of 0.0001, any statistical investigation requires very large data sets exceeding 100,000 samples. In the present investigation, this was achieved by capturing long PIV records using image high magnification. To investigate the influence of Reynolds number and pressure gradient, the measurements were performed in turbulent boundary layers in both zero pressure gradient (ZPG) and adverse pressure gradient (APG) conditions. The PIV measurements were performed in the TBL wind tunnel of Lille which features a test section length of 20 m and cross-section of 2 x 1 m^2. A ramp model placed inside the tunnel introduced APG conditions. Both visual inspection of the raw data and a dedicated processing scheme to retrieve the unsteady wall shear stress were used to quantify the flow reversal events. The occurrence of the self-similar flow reversals was found to weakly depend on the Reynolds numbers in ZPG and are roughly doubled in frequency in the APG condition.

Item URL in elib:https://elib.dlr.de/121145/
Document Type:Conference or Workshop Item (Speech)
Title:Flow Reversal in Turbulent Boundary Layers with Varying Pressure Gradients
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Willert, ChristianChris.Willert (at) dlr.dehttps://orcid.org/0000-0002-1668-0181
Soria, JulioMonash University, VIC 3800, AustraliaUNSPECIFIED
Cuvier, ChristopheLMFL FRE3723, Centrale Lille, CNRS, Villeneuve d'Ascq, FranceUNSPECIFIED
Foucaut, Jean MarcLMFL FRE3723, Centrale Lille, CNRS, Villeneuve d'Ascq, FranceUNSPECIFIED
Laval, Jean PhilippeLMFL FRE3723, Centrale Lille, CNRS, Villeneuve d'Ascq, FranceUNSPECIFIED
Date:16 July 2018
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:turbulent boundary layer, wall shear stress, particle image velocimetry, PIV, particle tracking velocimetry, PTV, long-range micro PIV, turbulence, flow visualization, image-based velocimetry
Event Title:19th International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics
Event Location:Lisbon, Portugal
Event Type:international Conference
Event Dates:16.-19. Jul. 2018
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:propulsion systems
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Virtual Engine and Validation methods
Location: Köln-Porz
Institutes and Institutions:Institute of Propulsion Technology > Engine Measurement Systems
Deposited By: Willert, Dr.phil. Christian
Deposited On:30 Jul 2018 09:30
Last Modified:31 Jul 2019 20:18

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