Turbulent Flow over a Flexible Wall Undergoing a Streamwise Traveling Wavy Motion
Direct numerical simulation is used to study the turbulent flow over a smooth wavy wall undergoing transverse motion in the form of a streamwise travelling wave. The Reynolds number based on the mean velocity U of the external flow and wall motion wavelength λ is 10 170; the wave steepness is 2πa...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | en_US |
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Cambridge University Press
2005
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| Subjects: | |
| Online Access: | http://hdl.handle.net/1721.1/25621 |
| _version_ | 1811090947185836032 |
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| author | Shen, Lian Zhang, Xiang Yue, Dick K.P. Triantafyllou, Michael S. |
| author_facet | Shen, Lian Zhang, Xiang Yue, Dick K.P. Triantafyllou, Michael S. |
| author_sort | Shen, Lian |
| collection | MIT |
| description | Direct numerical simulation is used to study the turbulent flow over a smooth wavy
wall undergoing transverse motion in the form of a streamwise travelling wave. The
Reynolds number based on the mean velocity U of the external flow and wall motion
wavelength λ is 10 170; the wave steepness is 2πa/λ = 0.25 where a is the travelling
wave amplitude. A key parameter for this problem is the ratio of the wall motion
phase speed c to U, and results are obtained for c/U in the range of â1.0 to 2.0 at
0.2 intervals. For negative c/U, we find that flow separation is enhanced and a large
drag force is produced. For positive c/U, the results show that as c/U increases from
zero, the separation bubble moves further upstream and away from the wall, and is
reduced in strength. Above a threshold value of c/U ≈ 1, separation is eliminated;
and, relative to small- c/U cases, turbulence intensity and turbulent shear stress are
reduced significantly. The drag force decreases monotonically as c/U increases while the power required for the transverse motion generally increases for large c/U; the
net power input is found to reach a minimum at c/U ≈ 1.2 (for fixed U). The results
obtained in this study provide physical insight into the study of fish-like swimming
mechanisms in terms of drag reduction and optimal propulsive efficiency. |
| first_indexed | 2024-09-23T14:54:31Z |
| format | Article |
| id | mit-1721.1/25621 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T14:54:31Z |
| publishDate | 2005 |
| publisher | Cambridge University Press |
| record_format | dspace |
| spelling | mit-1721.1/256212019-04-12T11:21:52Z Turbulent Flow over a Flexible Wall Undergoing a Streamwise Traveling Wavy Motion Shen, Lian Zhang, Xiang Yue, Dick K.P. Triantafyllou, Michael S. Turbulence reynolds number numerical simulation Direct numerical simulation is used to study the turbulent flow over a smooth wavy wall undergoing transverse motion in the form of a streamwise travelling wave. The Reynolds number based on the mean velocity U of the external flow and wall motion wavelength λ is 10 170; the wave steepness is 2πa/λ = 0.25 where a is the travelling wave amplitude. A key parameter for this problem is the ratio of the wall motion phase speed c to U, and results are obtained for c/U in the range of â1.0 to 2.0 at 0.2 intervals. For negative c/U, we find that flow separation is enhanced and a large drag force is produced. For positive c/U, the results show that as c/U increases from zero, the separation bubble moves further upstream and away from the wall, and is reduced in strength. Above a threshold value of c/U ≈ 1, separation is eliminated; and, relative to small- c/U cases, turbulence intensity and turbulent shear stress are reduced significantly. The drag force decreases monotonically as c/U increases while the power required for the transverse motion generally increases for large c/U; the net power input is found to reach a minimum at c/U ≈ 1.2 (for fixed U). The results obtained in this study provide physical insight into the study of fish-like swimming mechanisms in terms of drag reduction and optimal propulsive efficiency. 2005-08-23T06:10:50Z 2005-08-23T06:10:50Z 2003 Article http://hdl.handle.net/1721.1/25621 Journal of Fluid Mechanics, 484, p.197-221 (2003) en_US Copyright: Cambridge University Press This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder. 484296 bytes application/pdf application/pdf Cambridge University Press |
| spellingShingle | Turbulence reynolds number numerical simulation Shen, Lian Zhang, Xiang Yue, Dick K.P. Triantafyllou, Michael S. Turbulent Flow over a Flexible Wall Undergoing a Streamwise Traveling Wavy Motion |
| title | Turbulent Flow over a Flexible Wall Undergoing a Streamwise Traveling Wavy Motion |
| title_full | Turbulent Flow over a Flexible Wall Undergoing a Streamwise Traveling Wavy Motion |
| title_fullStr | Turbulent Flow over a Flexible Wall Undergoing a Streamwise Traveling Wavy Motion |
| title_full_unstemmed | Turbulent Flow over a Flexible Wall Undergoing a Streamwise Traveling Wavy Motion |
| title_short | Turbulent Flow over a Flexible Wall Undergoing a Streamwise Traveling Wavy Motion |
| title_sort | turbulent flow over a flexible wall undergoing a streamwise traveling wavy motion |
| topic | Turbulence reynolds number numerical simulation |
| url | http://hdl.handle.net/1721.1/25621 |
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