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Hydrodynamic analysis of nonlinear waves for assessment of coastal ecosystems

用于评估沿海生态系统的非线性波浪水动力分析

基本信息

批准号：
10450385
负责人：
MORI Kazu-hiro
金额：
$ 5.76万
依托单位：
Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10450385/
关键词：
Costal ecosystems environmental conservation nonlinear waves seawater percolation

项目摘要

In the present research, it was found that nonlinear breaking waves on a sloping beach caused sea water percolation into sea bed. The flow visualization showed that the water moved into the sea bed with radial direction neat the run-up point, and then returned to the surface near the breaking point.Measurement of the pressure on the surface of sea bed revealed the relation between the percolating water flow and the time averaged pressure on the surface of sea bed. The time averaged pressure was found to be estimated through the Wave Set-up and Set-down based on the nonlinear water wave theory.The pressure distribution in the sea bed was calculated assuming Darcy's law. The pressure on the boundary was derived from Wave Set-up and Set-down. Laplace equation for the time-averaged pressure was solved by finite difference method. The calculated velocity distribution was in accordance with the observed flow pattern.Finally, the relation between the slope of beach and percolation in the surf zone was made clear through the numerical simulation.Internal flow inside the surf zone closely relates to the purging of silt and the biological activities. Because the sea water is cleaned up by percolation into sea bed and water flow into sea bed is transporting a kind of nutrients and oxygen to benthos in the surf zone. The present research threw light on the relation between waves and costal ecosystems.

在本研究中发现，非线性破碎波在倾斜海滩上引起海水向海床渗透。流动可视化结果表明，水在上升点附近沿径向进入海床，然后在破裂点附近返回海面。通过对海床表面压力的测量，揭示了渗透水流与海床表面时间平均压力之间的关系。基于非线性水波理论，通过波浪的设置和设置，可以估计出时间平均压力。采用达西定律计算了海底压力分布。边界上的压力来源于波浪的升降。采用有限差分法求解时间平均压力的拉普拉斯方程。计算得到的速度分布与实测流型基本一致。最后，通过数值模拟，明确了滩涂坡度与冲浪带渗流的关系。冲浪带内部的流动与泥沙的冲刷和生物活动密切相关。因为海水通过渗透进入海床而被净化，流入海床的水流将一种营养物质和氧气输送给了冲浪区的底栖动物。目前的研究揭示了波浪与沿海生态系统之间的关系。