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

Embargo End Date
2018-11-01

Type
Article

Authors
Bouremel, Yann
Mitsudharmadi, Hatsari
Budiman, Alexander C.
Winoto, Sonny H.

KAUST Department
Clean Combustion Research Center

Online Publication Date
2016-11-01

Print Publication Date
2017-04

Date
2016-11-01

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=0ωz=0. It has also been found that the vorticity ωzωz 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.

Citation
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: 75–82. Available: http://dx.doi.org/10.1016/j.expthermflusci.2016.10.034.

Acknowledgements
The authors express their appreciation to Mr. Lucius Sim and Mr. M.N. Adha b Jamaludin for their help in setting up the experimental rig and in collecting the experimental data.

Publisher
Elsevier BV

Journal
Experimental Thermal and Fluid Science

DOI
10.1016/j.expthermflusci.2016.10.034

Additional Links
http://dx.doi.org/10.1016/j.expthermflusci.2016.10.034https://discovery.ucl.ac.uk/1531892/1/Bouremel_Experimental-Thermal-and-Fluid-Science_discovery.pdf

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