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Characterization of counter-rotating streamwise vortices in flat rectangular channel with one-sided wavy wall

Bouremel, Y; Mitsudharmadi, H; Budiman, AC; Winoto, SH; (2017) Characterization of counter-rotating streamwise vortices in flat rectangular channel with one-sided wavy wall. Experimental Thermal and Fluid Science , 82 pp. 75-82. 10.1016/j.expthermflusci.2016.10.034. Green open access

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Abstract

Particle Image Velocimetry (PIV) has been used to characterize the evolution of counter-rotating streamwise vortices in a rectangular channel with one sided wavy surface. The vortices were created by a uniform set of saw-tooth carved over the leading edge of a flat plate at the entrance of a flat rectangular channel with one-sided wavy wall. PIV measurements were taken over the spanwise and streamwise planes at different locations and at Reynolds number of 2500. Two other Reynolds numbers of 2885 and 3333 have also been considered for quantification purpose. Pairs of counter-rotating streamwise vortices have been shown experimentally to be centred along the spanwise direction at the saw-tooth valley where the vorticity ωz=0. It has also been found that the vorticity ωz of the pairs of counter-rotating vortices decreases along the streamwise direction, and increases with the Reynolds number. Moreover, different quantifications of such counter-rotating vortices have been discussed such as their size, boundary layer, velocity profile and vorticity. The current study shows that the mixing due to the wall shear stress of counter-rotating streamwise vortices as well as their averaged viscous dissipation rate of kinetic energy decrease over flat and adverse pressure gradient surfaces while increasing over favourable pressure gradient surfaces. Finally, it was also demonstrated that the main direction of stretching is orientated at around 45° with the main flow direction.

Type: Article
Title: Characterization of counter-rotating streamwise vortices in flat rectangular channel with one-sided wavy wall
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.expthermflusci.2016.10.034
Publisher version: http://doi.org/10.1016/j.expthermflusci.2016.10.03...
Language: English
Additional information: © 2016 Elsevier Inc. All rights reserved. This manuscript version is made available under a Creative Commons Attribution Non-commercial Non-derivative 4.0 International license (CC BY-NC-ND 4.0). This license allows you to share, copy, distribute and transmit the work for personal and non-commercial use providing author and publisher attribution is clearly stated. Further details about CC BY licenses are available at https://creativecommons.org/licenses/. Access may be initially restricted by the publisher.
Keywords: Counter-rotating vortices; Wavy wall; Vorticity; Mixing; Stretching
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Ophthalmology
URI: https://discovery.ucl.ac.uk/id/eprint/1531892
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