On the limits of wavy cylinder wavelength and amplitude for effective wake and vortex-shedding control
An experimental time-resolved particle-image velocimetry study was conducted on wavy cylinders possessing wavelength (λ) and amplitude (a) combinations that are significantly different from earlier studies at ReDm = 2700. Results show that vortex formation length increases as the wavelength decrease...
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sg-ntu-dr.10356-1729472024-01-03T06:06:06Z On the limits of wavy cylinder wavelength and amplitude for effective wake and vortex-shedding control New, Tze How Lim, H. D. Chen, Chiun Hsun Lua, Kim Boon School of Mechanical and Aerospace Engineering Engineering::Mechanical engineering Wavy Cylinder Flow Separation An experimental time-resolved particle-image velocimetry study was conducted on wavy cylinders possessing wavelength (λ) and amplitude (a) combinations that are significantly different from earlier studies at ReDm = 2700. Results show that vortex formation length increases as the wavelength decreases from λ/Dm = 2.4 to 1.2, but decreases when the latter decreases to λ/Dm = 0.6. Amplitude increments lead to significant vortex formation length growths and reductions at the saddles/nodes of λ/Dm = 2.4 and 1.2 wavy cylinders, respectively. In contrast, λ/Dm = 0.6 wavy cylinders produce significantly shorter vortex formation lengths like a baseline cylinder, regardless of amplitude. Regular reversed flow “lobes” are observed for λ/Dm = 2.4 and 1.2 wavy cylinders, but not λ/Dm = 0.6 ones, which lead to variations in the spanwise vortex formation lengths. Proper orthogonal decomposition (POD) analysis shows that only a/Dm = 0.4, λ/Dm = 0.6 wavy cylinder has the same vortex-shedding frequency as the baseline cylinder. Other POD results also demonstrate that the vortex-shedding behaviour between λ/Dm = 0.6 wavy and baseline cylinder is very similar. The present study shows that there exists a minimal wavelength below which that coherent streamwise vortices will not be produced and wake control benefits of wavy cylinders will be considerably reduced. Nanyang Technological University The authors acknowledge the support for this study by the School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, and the Higher Education Sprout Project of the National Yang Ming Chiao Tung University and Ministry of Education (MOE), Taiwan. 2024-01-03T06:06:06Z 2024-01-03T06:06:06Z 2023 Journal Article New, T. H., Lim, H. D., Chen, C. H. & Lua, K. B. (2023). On the limits of wavy cylinder wavelength and amplitude for effective wake and vortex-shedding control. Journal of Marine Science and Technology, 28(3), 597-614. https://dx.doi.org/10.1007/s00773-023-00943-8 0948-4280 https://hdl.handle.net/10356/172947 10.1007/s00773-023-00943-8 2-s2.0-85161471188 3 28 597 614 en Journal of Marine Science and Technology © 2023 The Author(s), under exclusive licence to The Japan Society of Naval Architects and Ocean Engineers (JASNAOE). All rights reserved. |
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Engineering::Mechanical engineering Wavy Cylinder Flow Separation New, Tze How Lim, H. D. Chen, Chiun Hsun Lua, Kim Boon On the limits of wavy cylinder wavelength and amplitude for effective wake and vortex-shedding control |
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An experimental time-resolved particle-image velocimetry study was conducted on wavy cylinders possessing wavelength (λ) and amplitude (a) combinations that are significantly different from earlier studies at ReDm = 2700. Results show that vortex formation length increases as the wavelength decreases from λ/Dm = 2.4 to 1.2, but decreases when the latter decreases to λ/Dm = 0.6. Amplitude increments lead to significant vortex formation length growths and reductions at the saddles/nodes of λ/Dm = 2.4 and 1.2 wavy cylinders, respectively. In contrast, λ/Dm = 0.6 wavy cylinders produce significantly shorter vortex formation lengths like a baseline cylinder, regardless of amplitude. Regular reversed flow “lobes” are observed for λ/Dm = 2.4 and 1.2 wavy cylinders, but not λ/Dm = 0.6 ones, which lead to variations in the spanwise vortex formation lengths. Proper orthogonal decomposition (POD) analysis shows that only a/Dm = 0.4, λ/Dm = 0.6 wavy cylinder has the same vortex-shedding frequency as the baseline cylinder. Other POD results also demonstrate that the vortex-shedding behaviour between λ/Dm = 0.6 wavy and baseline cylinder is very similar. The present study shows that there exists a minimal wavelength below which that coherent streamwise vortices will not be produced and wake control benefits of wavy cylinders will be considerably reduced. |
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School of Mechanical and Aerospace Engineering |
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School of Mechanical and Aerospace Engineering New, Tze How Lim, H. D. Chen, Chiun Hsun Lua, Kim Boon |
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Article |
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New, Tze How Lim, H. D. Chen, Chiun Hsun Lua, Kim Boon |
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New, Tze How |
title |
On the limits of wavy cylinder wavelength and amplitude for effective wake and vortex-shedding control |
title_short |
On the limits of wavy cylinder wavelength and amplitude for effective wake and vortex-shedding control |
title_full |
On the limits of wavy cylinder wavelength and amplitude for effective wake and vortex-shedding control |
title_fullStr |
On the limits of wavy cylinder wavelength and amplitude for effective wake and vortex-shedding control |
title_full_unstemmed |
On the limits of wavy cylinder wavelength and amplitude for effective wake and vortex-shedding control |
title_sort |
on the limits of wavy cylinder wavelength and amplitude for effective wake and vortex-shedding control |
publishDate |
2024 |
url |
https://hdl.handle.net/10356/172947 |
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1787590731000446976 |