| An experimental study of the spatial structures of the instabilities of longshore currents on plane beaches |
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| 作者姓名： | REN Chunping ZOU Zhili |
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| 作者单位： | College of Water Resource Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China;State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China;State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China |
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| 基金项目： | The National Natural Science Foundation of China under contract Nos 50479053 and 10672034; the Program for the Changjiang Scholars and the Innovative Research Team in the University of China; the Shanxi Province Natural Science Foundation for Young Scholar of China under contract No.2011021025-1. |
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| 摘 要： | A laboratory experiment on alongshore currents is conducted for two plane beaches with slopes 1:40 and 1:100 to investigate the instability of alongshore currents.The dye release experiment is also performed synchronously in surf zone.Complicated and strongly unstable motions of alongshore currents are observed in the experiment.To examine the spatial and temporal variations of the shear instabilities of longshore clearly,dye batches are released in surf zone.The deformation of the dye patch is observed efficiently and effectively with charge coupled device(CCD) system.Some essential characteristics of the shear instability are validated from the results of image analyses of the temporal variation of the dye patch.The influences of alongshore currents,Stokes drift,large-scale vorticity and the shear instabilities on the transport of dye are analyzed using the collected images.The spatial structure of the instabilities of longshore currents is studied by analyzing collected images of the dye patch.And the phase velocity of the meandering movements is obtained through measuring the movement distances of the oscillations of dye patch in alongshore direction with time.The results suggest that the propagation speed of the shear instability is approximately 50%-75% of maximum of mean alongshore currents for irregular and regular waves.The calculated propagation speed using a linear instability analysis theory is compared with the experimental results.The comparison shows agreements between them.
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| 关 键 词： | alongshore currents shear instability spatial structures linear instability analysis |
| 收稿时间： | 2011/11/15 0:00:00 |
| 修稿时间： | 2012/5/15 0:00:00 |
An experimental study of the spatial structures of the instabilities of longshore currents on plane beaches |
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| REN Chunping,ZOU Zhili.An experimental study of the spatial structures of the instabilities of longshore currents on plane beaches[J].Acta Oceanologica Sinica,2012,31(6):32-45. |
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| Authors: | REN Chunping and ZOU Zhili |
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| Institution: | 1.College of Water Resource Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China;State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China2.State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China |
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| Abstract: | A laboratory experiment on alongshore currents is conducted for two plane beaches with slopes 1:40 and 1:100 to investigate the instability of alongshore currents. The dye release experiment is also performed synchronously in surf zone. Complicated and strongly unstable motions of alongshore currents are observed in the experiment. To examine the spatial and temporal variations of the shear instabilities of longshore clearly, dye batches are released in surf zone. The deformation of the dye patch is observed efficiently and effectively with charge coupled device (CCD) system. Some essential characteristics of the shear instability are validated from the results of image analyses of the temporal variation of the dye patch. The influences of alongshore currents, Stokes drift, large-scale vorticity and the shear instabilities on the transport of dye are analyzed using the collected images. The spatial structure of the instabilities of longshore currents is studied by analyzing collected images of the dye patch. And the phase velocity of the meandering movements is obtained through measuring the movement distances of the oscillations of dye patch in alongshore direction with time. The results suggest that the propagation speed of the shear instability is approximately 50%-75% of maximum of mean alongshore currents for irregular and regular waves. The calculated propagation speed using a linear instability analysis theory is compared with the experimental results. The comparison shows agreements between them. |
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| Keywords: | alongshore currents shear instability spatial structures linear instability analysis |
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