Particle image velocimetry measurements of bed-shear stress induced by wall-bounded swirling jets
This study presents measurements of the bed shear stress associated with the three-dimensional boundary layer induced by a wall-bounded swirling jet. The velocity profile within the viscous sublayer was measured in detail using a high-resolution particle image velocimetry system that enables direct...
| Main Authors: | , , |
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| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/159624 |
| _version_ | 1826112103710195712 |
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| author | Wei, Maoxing Chiew, Yee-Meng Cheng, Nian-Sheng |
| author2 | School of Civil and Environmental Engineering |
| author_facet | School of Civil and Environmental Engineering Wei, Maoxing Chiew, Yee-Meng Cheng, Nian-Sheng |
| author_sort | Wei, Maoxing |
| collection | NTU |
| description | This study presents measurements of the bed shear stress associated with the three-dimensional boundary layer induced by a wall-bounded swirling jet. The velocity profile within the viscous sublayer was measured in detail using a high-resolution particle image velocimetry system that enables direct evaluation of the bed shear stress from the velocity gradient at the wall. The three-dimensional flow field was reconstructed based on the measurements conducted in a series of intersecting streamwise and transverse planes. At each intersection, the resultant bed shear stress was calculated as the vector sum of its components. The results show that the planar distribution of the bed shear stress is highly asymmetrical about the propeller axis due to the swirling rotation, which furnishes a description of how the jet path migrates over the plane boundary under the swirling effect. Compared with the expected scour hole that the swirling jet could induce on an erodible bed, the results presented in this study shed light on a qualitative understanding of the distinctive jet impingement mechanisms associated with rigid and erodible bed boundaries. Moreover, a close examination of the mean velocity distributions of both individual and resultant velocities reveals a consistent discrepancy from the universal logarithmic law in the log layer, in which the velocity distribution is subjected to outer layer bulk flow properties, thereby highlighting the evident difference in boundary layer flow between an impinging jet and canonical wall-bounded flows. |
| first_indexed | 2024-10-01T03:01:47Z |
| format | Journal Article |
| id | ntu-10356/159624 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T03:01:47Z |
| publishDate | 2022 |
| record_format | dspace |
| spelling | ntu-10356/1596242022-06-30T04:38:07Z Particle image velocimetry measurements of bed-shear stress induced by wall-bounded swirling jets Wei, Maoxing Chiew, Yee-Meng Cheng, Nian-Sheng School of Civil and Environmental Engineering Engineering::Civil engineering Boundary Layer Bed Shear Stress This study presents measurements of the bed shear stress associated with the three-dimensional boundary layer induced by a wall-bounded swirling jet. The velocity profile within the viscous sublayer was measured in detail using a high-resolution particle image velocimetry system that enables direct evaluation of the bed shear stress from the velocity gradient at the wall. The three-dimensional flow field was reconstructed based on the measurements conducted in a series of intersecting streamwise and transverse planes. At each intersection, the resultant bed shear stress was calculated as the vector sum of its components. The results show that the planar distribution of the bed shear stress is highly asymmetrical about the propeller axis due to the swirling rotation, which furnishes a description of how the jet path migrates over the plane boundary under the swirling effect. Compared with the expected scour hole that the swirling jet could induce on an erodible bed, the results presented in this study shed light on a qualitative understanding of the distinctive jet impingement mechanisms associated with rigid and erodible bed boundaries. Moreover, a close examination of the mean velocity distributions of both individual and resultant velocities reveals a consistent discrepancy from the universal logarithmic law in the log layer, in which the velocity distribution is subjected to outer layer bulk flow properties, thereby highlighting the evident difference in boundary layer flow between an impinging jet and canonical wall-bounded flows. 2022-06-29T06:42:19Z 2022-06-29T06:42:19Z 2020 Journal Article Wei, M., Chiew, Y. & Cheng, N. (2020). Particle image velocimetry measurements of bed-shear stress induced by wall-bounded swirling jets. Journal of Engineering Mechanics, 146(6), 04020052-. https://dx.doi.org/10.1061/(ASCE)EM.1943-7889.0001781 0733-9399 https://hdl.handle.net/10356/159624 10.1061/(ASCE)EM.1943-7889.0001781 2-s2.0-85083235754 6 146 04020052 en Journal of Engineering Mechanics © 2020 American Society of Civil Engineers. All rights reserved. |
| spellingShingle | Engineering::Civil engineering Boundary Layer Bed Shear Stress Wei, Maoxing Chiew, Yee-Meng Cheng, Nian-Sheng Particle image velocimetry measurements of bed-shear stress induced by wall-bounded swirling jets |
| title | Particle image velocimetry measurements of bed-shear stress induced by wall-bounded swirling jets |
| title_full | Particle image velocimetry measurements of bed-shear stress induced by wall-bounded swirling jets |
| title_fullStr | Particle image velocimetry measurements of bed-shear stress induced by wall-bounded swirling jets |
| title_full_unstemmed | Particle image velocimetry measurements of bed-shear stress induced by wall-bounded swirling jets |
| title_short | Particle image velocimetry measurements of bed-shear stress induced by wall-bounded swirling jets |
| title_sort | particle image velocimetry measurements of bed shear stress induced by wall bounded swirling jets |
| topic | Engineering::Civil engineering Boundary Layer Bed Shear Stress |
| url | https://hdl.handle.net/10356/159624 |
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