| NING Dezhi,DU Jun,BAI Wei,ZHANG Chongwei,TENG Bin. 2018. Numerical modelling of nonlinear extreme waves in presence of wind. Acta Oceanologica Sinica, 37(9):90－98 |
| Numerical modelling of nonlinear extreme waves in presence of wind |
| 风压作用下非线性极端波浪的数值模拟 |
| Received:August 04, 2017 |
| DOI：10.1007/s13131-018-1268-3 |
| Key words:extreme waves fully nonlinear numerical wave flume higher-order boundary element wave focusing Jeffreys' sheltering mechanism |
| 中文关键词: 极端波浪 完全非线性数值波浪水槽 高阶边界元 波浪聚焦 Jeffrey遮蔽理论 |
| 基金项目:The National Natural Science Foundation of China under contract Nos 51679036, 51490672 and 51709038; the Fundamental Research Funds for the Central Universities under contract Nos DUT17GJ202 and DUT16RC(3)113; the Open Foundation of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering under contract No. 2016490111. |
| Author Name | Affiliation | E-mail | | NING Dezhi | State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China
State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116023, China | | | DU Jun | State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116023, China
China Communications Planning and Design Institute for Water Transportation Ltd., Beijing 100007, China | | | BAI Wei | School of Computing, Mathematics and Digital Technology, Manchester Metropolitan University, Manchester M1 5GD, UK | | | ZHANG Chongwei | State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116023, China | chongweizhang@dlut.edu.cn | | TENG Bin | State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116023, China | |
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| Abstract: |
| A numerical wave flume with fully nonlinear free surface boundary conditions is adopted to investigate the temporal characteristics of extreme waves in the presence of wind at various speeds. Incident wave trains are numerically generated by a piston-type wave maker, and the wind-excited pressure is introduced into dynamic boundary conditions using a pressure distribution over steep crests, as defined by Jeffreys' sheltering mechanism. A boundary value problem is solved by a higher-order boundary element method (HOBEM) and a mixed Eulerian-Lagrangian time marching scheme. The proposed model is validated through comparison with published experimental data from a focused wave group. The influence of wind on extreme wave properties, including maximum extreme wave crest, focal position shift, and spectrum evolution, is also studied. To consider the effects of the wind-driven currents on a wave evolution, the simulations assume a uniform current over varying water depth. The results show that wind causes weak increases in the extreme wave crest, and makes the nonlinear energy transfer non-reversible in the focusing and defocusing processes. The numerical results also provide a comparison to demonstrate the shifts at focal points, considering the combined effects of the winds and the wind-driven currents. |
| 中文摘要: |
| 本文在时域非线性数值波浪水槽中，研究了不同风速条件下极端波浪的特性。采用推板造波的方式生成非线性波浪，基于Jeffrey遮蔽理论将风压项引入自由面动力学边界条件来模拟风压作用，通过高阶边界元法和混合欧拉-拉格朗日时间步进法来求解初边值问题。通过与已发表的聚焦波群实验结果对比验证了该数值模型的准确性，并研究了风压对极端波浪的最大波高、聚焦位置的偏移和波浪谱的演变等波浪性质的影响。本文进一步在数值波浪水槽中引入均匀水流，来模拟风生流对波浪演变的影响。结果表明，风压的存在会少量增大极端波浪的最大波高，波浪的聚焦和解焦过程伴随着明显的能量传递，并且风生流进一步导致了波浪聚焦位置的偏移。 |
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