| Experimental Study on the Bed Shear Stress Under Breaking Waves |
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| 作者姓名： | HAO Si-yu XIA Yun-feng XU Hua |
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| 作者单位： | Nanjing Hydraulic Research Institute, Nanjing 210029, China;College of Harbor, Coastal and Offshore Engineering, Hohai University, Nanjing 210098, China;The State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing 210098, China;Key Laboratory of Port, Waterway and Sedimentation Engineering of Ministry of Transport, Nanjing 210024, China,Nanjing Hydraulic Research Institute, Nanjing 210029, China;The State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing 210098, China;Key Laboratory of Port, Waterway and Sedimentation Engineering of Ministry of Transport, Nanjing 210024, China,Nanjing Hydraulic Research Institute, Nanjing 210029, China;The State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing 210098, China;Key Laboratory of Port, Waterway and Sedimentation Engineering of Ministry of Transport, Nanjing 210024, China |
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| 基金项目： | This study was financially supported by the National Key Scientific Instrument and Equipment Development Project (Grant No. 2013YQ04091108),and the National Natural Science Foundation of China (Grant No. 51309158). |
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| 摘 要： | The object of present study is to investigate the bed shear stress on a slope under regular breaking waves by a novel instrument named Micro-Electro-Mechanical System (MEMS) flexible hot-film shear stress sensor. The sensors were calibrated before application, and then a wave flume experiment was conducted to study the bed shear stress for the case of regular waves spilling and plunging on a 1:15 smooth PVC slope. The experiment shows that the sensor is feasible for the measurement of the bed shear stress under breaking waves. For regular incident waves, the bed shear stress is mainly periodic in both outside and inside the breaking point. The fluctuations of the bed shear stress increase significantly after waves breaking due to the turbulence and vortexes generated by breaking waves. For plunging breaker, the extreme value of the mean maximum bed shear stress appears after the plunging point, and the more violent the wave breaks, the more dramatic increase of the maximum bed shear stress will occur. For spilling breaker, the increase of the maximum bed shear stress along the slope is gradual compared with the plunging breaker. At last, an empirical equation about the relationship between the maximum bed shear stress and the surf similarity parameter is given, which can be used to estimate the maximum bed shear stress under breaking waves in practice.
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| 关 键 词： | bed shear stress direct measurement shear stress sensor spilling breaker plunging breaker |
| 收稿时间： | 2017/3/3 0:00:00 |
| 修稿时间： | 2017/4/26 0:00:00 |
Experimental Study on the Bed Shear Stress Under Breaking Waves |
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| HAO Si-yu,XIA Yun-feng,XU Hua.Experimental Study on the Bed Shear Stress Under Breaking Waves[J].Ocean Engineering,2017,31(3):308-316. |
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| Authors: | HAO Si-yu XIA Yun-feng and XU Hua |
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| Institution: | Nanjing Hydraulic Research Institute, Nanjing 210029, China;College of Harbor, Coastal and Offshore Engineering, Hohai University, Nanjing 210098, China;The State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing 210098, China;Key Laboratory of Port, Waterway and Sedimentation Engineering of Ministry of Transport, Nanjing 210024, China,Nanjing Hydraulic Research Institute, Nanjing 210029, China;The State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing 210098, China;Key Laboratory of Port, Waterway and Sedimentation Engineering of Ministry of Transport, Nanjing 210024, China and Nanjing Hydraulic Research Institute, Nanjing 210029, China;The State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing 210098, China;Key Laboratory of Port, Waterway and Sedimentation Engineering of Ministry of Transport, Nanjing 210024, China |
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| Abstract: | The object of present study is to investigate the bed shear stress on a slope under regular breaking waves by a novel instrument named Micro-Electro-Mechanical System (MEMS) flexible hot-film shear stress sensor. The sensors were calibrated before application, and then a wave flume experiment was conducted to study the bed shear stress for the case of regular waves spilling and plunging on a 1:15 smooth PVC slope. The experiment shows that the sensor is feasible for the measurement of the bed shear stress under breaking waves. For regular incident waves, the bed shear stress is mainly periodic in both outside and inside the breaking point. The fluctuations of the bed shear stress increase significantly after waves breaking due to the turbulence and vortexes generated by breaking waves. For plunging breaker, the extreme value of the mean maximum bed shear stress appears after the plunging point, and the more violent the wave breaks, the more dramatic increase of the maximum bed shear stress will occur. For spilling breaker, the increase of the maximum bed shear stress along the slope is gradual compared with the plunging breaker. At last, an empirical equation about the relationship between the maximum bed shear stress and the surf similarity parameter is given, which can be used to estimate the maximum bed shear stress under breaking waves in practice. |
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| Keywords: | bed shear stress direct measurement shear stress sensor spilling breaker plunging breaker |
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