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Analysis of flapping motion of reattaching shear layer behind a two-dimensionalbackward-facing step

Ma, Xingyu and Schröder, Andreas (2017) Analysis of flapping motion of reattaching shear layer behind a two-dimensionalbackward-facing step. Physics of Fluids. American Institute of Physics (AIP). DOI: 10.1063/1.4996622 ISSN 1070-6631

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Official URL: https://doi.org/10.1063/1.4996622


An experimental investigation was carried out on the flapping motion of a turbulent reattaching shear layer downstream of a two-dimensional backward-facing step. The Reynolds number was 2.0 x 104, based on the free-stream velocity and the step height. The aim of this study is to analyze the flapping motion, which is featured unsteadiness of the reattaching shear layer, and its interaction with the recirculation region. High-resolution planar particle image velocimetry was used to measure the separated and reattaching shear layer in a horizontal-vertical plane. The velocity vector fields have shown the reattaching shear layer considerably flaps upwards and downwards as much in scale as approximately one step height from the middle part of recirculation region to the reattachment area. As a result, the recirculation region varies in size and the reattachment point shifts upstream and downstream. By applying singular value decomposition and proper orthogonal decomposition, the flapping motion is decomposed into multiple spatial rnodes, each of which represents interactions between the reattaching shear layer and recirculation region. In particular, the unsteady movement of the reattachment point is highly correlated with the flapping motion, and so is the maximum reverse flow. As a result, the flapping motion contributes substantial parts of the Reynolds shear stress and turbulent kinetic energy within the shear layer in the lauer half of the reattachment length

Item URL in elib:https://elib.dlr.de/117047/
Document Type:Article
Additional Information:PHYSICS OF FLUIDS 29, 115104 (2017)
Title:Analysis of flapping motion of reattaching shear layer behind a two-dimensionalbackward-facing step
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Ma, XingyuXingyu.Ma (at) dlr.deUNSPECIFIED
Schröder, AndreasAndreas.Schroeder (at) dlr.deUNSPECIFIED
Journal or Publication Title:Physics of Fluids
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.1063/1.4996622
Publisher:American Institute of Physics (AIP)
Keywords:Large-scale low-frequency, two-dimensional backward-facing step, velocity vector fields, particle image velocimetry
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Simulation and Validation
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Experimental Methods, GO
Deposited By: Bachmann, Barbara
Deposited On:13 Dec 2017 14:38
Last Modified:23 Jan 2020 04:20

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