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热带海洋学报

• • 上一篇    

基于XBeach-NH的大糙率礁面波浪运动数值模拟

姚宇1, 2, 刘小娜1,, 周宝宝1,, 周婷1, 2   

  1. 1. 长沙理工大学水利与海洋工程学院, 湖南 长沙 410114;

    2. 水沙科学与水灾害防治湖南省重点实验室, 湖南 长沙 410114

  • 收稿日期:2024-11-20 修回日期:2025-02-19 接受日期:2025-02-24
  • 通讯作者: 周婷
  • 基金资助:
    国家重点研发计划课题(2021YFC3100500); 长沙理工大学2023年研究生创新项目(CSLGCX23058)

Numerical simulation of wave motions over reef surface with large roughness based on the XBeach-NH

YAO Yu1, 2, LIU Xiaona1, ZHOU Baobao1, ZHOU Ting1, 2   

  1. 1. School of Hydraulic and Ocean Engineering, Changsha University of Science & Technology, Changsha 410114, China;

    2. Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province, Changsha 410114, China

  • Received:2024-11-20 Revised:2025-02-19 Accepted:2025-02-24
  • Supported by:

     National Key Research and Development Program of China(2021YFC3100500); Changsha University of Science and Technology 2023 graduate student innovation project (CSLGCX23058)

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摘要： 本文采用XBeach-NH模型添加了基于Morison方程的拖曳力项，对大糙率礁面的波浪的运动特征及礁面拖曳力系数进行了数值模拟仿真分析，通过对光滑礁面和粗糙礁面上不同位置自由液面时间序列以及波高和平均水位沿礁分布对模型进行了验证。应用校核好的数值模型对比分析光滑礁面和粗糙礁面时礁缘附近及礁坪上自由液面时空分布特征，最后利用XBeach-NH模型模拟的结果校核出所有粗糙礁面实验工况最优拖曳力系数值。结果表明，XBeach-NH模型能够较好地模拟波浪的沿礁运动过程，在其基础上加入基于Morison方程的拖曳力项能够合理地模拟粗糙礁面阻力特性。糙率单元的存在导致波浪受到更大的底部摩阻的损耗，粗糙礁面较于光滑礁面的沿礁的波高增水显著减小。波浪传播过程出现高阶谐波和自由波，光滑礁面和粗糙礁面均会出现二次甚至更高次谐波，礁面糙率单元的存在会明显减小二次谐波的量级。在粗糙礁面，糙率单元对波能的产生有明显耗散现象。小水深且波高较小时拖曳力系数较大，这与浅水时水流阻力增大有关，大周期（长波）时拖曳力系数较大，而波高较大（波浪的非线性较强）时拖曳力系数的变化取决于礁坪水深。研究珊瑚礁礁面大糙率影响下的波浪运动特性能够为台风浪等极端波浪影响下的珊瑚礁海岸防灾减灾提供科学依据。

关键词: 礁面糙率, XBeach-NH模型, 波浪传播变形, 珊瑚礁地形

Abstract: The XBeach-NH model is used to add the drag term based on the Morison equation, and the numerical simulation and analysis of the wave motion characteristics and the drag coefficient of the reef surface is carried out. The model is verified by the time series of free surface at different positions on the smooth and rough reef surfaces, including the distribution of wave height and mean water level along the reef. The validated numerical model is used to compare and analyze the spatial and temporal distribution characteristics of free surface near the reef edge and on the reef flat when the smooth reef surface and the rough reef surface exist. Finally, the results of XBeach-NH model simulation are used to examine the optimal drag coefficient values of all rough reef surface experimental conditions. The results show that the XBeach-NH model can satisfactorily simulate the wave motion along the reef, and the drag term based on the Morison equation can reasonably simulate the resistance characteristics of the rough reef surface. The existence of the roughness element causes the wave energy to be subjected to greater bottom frictional damping, and the wave height increase along the reef on the rough reef surface is significantly smaller than that on the smooth reef surface. Higher harmonics and free waves appear in the process of wave propagation, and the second or even higher harmonics appear on both smooth and rough reef surfaces. The existence of the reef roughness unit will significantly reduce the magnitude of the second harmonic. On the rough reef surface, the wave energy is obviously dissipated by the roughness element. The drag coefficient is larger when the water depth and the wave height are both small, which is related to the increase of flow resistance in shallow water. The drag coefficient is larger when the period is large (long wave), and the change of drag coefficient value depends on the water depth of the reef flat when the wave height is large (strong nonlinearity). Studying the wave motion characteristics under the influence of large roughness of coral reef surface can provide scientific basis for disaster prevention and mitigation of coral reef coast under the impact of extreme waves such as typhoon waves.

Key words: reef roughness, XBeach-NH model, wave transformation, coral reef topography