波浪通過橢圓形潛堤之變形

Wave Transformations over a Submerged Elliptic Breakwater

許朝敏(Chao-Min Hsu) ； 林銘崇(Ming-Chung Lin)

《海洋工程學刊》 10卷2期 (2010/12) Pp. 143-162

https://doi.org/10.6266/JCOE.2010.1002.01

摘要

本研究旨在應用布斯尼斯克方程式(Boussinesq equations)，探討波浪通過緩變地形橢圓形潛堤之變化。文中以Wei et al. (1995)所推導之全非線性布斯尼斯克方程式爲基礎，以Kennedy et al. (2000)建議加入碎波項以模擬波浪碎波，並使用Wei and Kirby (1995)所提出之數值計算方法，在計算領域內使用造波源函數加上一適當之消波邊界條件，以消除計算領域內產生之數值反射波，增加模式穩定性。與實驗值互相驗證結果顯示，無論在非碎波與碎波條件下，本模式對於波浪變形的模擬相當良好。在不同入射波角度(0°, 15°, 30°)計算結果顯示，當波浪通過緩變地形下橢圓形潛堤時，波浪會在潛堤後方產生波浪聚焦現象，而當波浪斜向入射時，聚焦區中心線與波浪入射角度一致；在相對水深較小條件下，其最大無因次波高值會較大。

關鍵字

布斯尼斯克方程式 ； 碎波 ； 橢圓形潛堤 ； 波浪聚焦

並列摘要

This study investigates wave transformations over a submerged elliptic breakwater on a sloping bottom by numerical calculations. The theoretical model is based on the fully nonlinear Boussinesq equation applied by Wet et al. (1995). The Bottom friction, wave breaking, and sub-grid lateral turbulent mixing as proposed by Kennedy et al. (2000), are also included in the equations. The numerical model utilizes the Fourth-Order Adams-Bashforth-Moulton Predictor-Corrector Scheme proposed by Wet and Kirby (1995) and is combined with a source function and absorbing boundary condition to enhance calculations stability. The numerical results and experiments appear to be in agreement with each other in non-breaking and breaking wave cases. Several numerical experiments are conducted for waves with incident angles of 0°, 15° and 30°. Numerical results show the phenomena of wave focus in the rear of the elliptic shoal. The wave focus region is located in the direction of the incident wave. Non-dimensional wave height increases as the relative water depth decreases.

並列關鍵字

Boussinesq equations ； wave breaking ； submerged elliptic breakwater ； wave focus