本研究主要是以Lynett & Liu(2004)所提出之多層型式之Boussinesq方程組為數值模式基礎，模擬正向規則波通過週期性系列潛堤時的情形。模式先以單層及雙層初步探討差異情形並與實驗比較。為探討堤前波浪反射現象時，考慮波浪因非線性效應所產生的高頻成分波，以三種分析方法求其反射率並予以討論之；另外於潛堤後方設立垂直壁面，模擬當布拉格共振發生時，堤後距離與波能變化的關係。由結果發現：模式驗證非線性效應需要空間成長，因此數值水槽若設計為短尺寸水槽，則多層之間水位波形並無明顯差異，因此本文的數值方法乃使用單層型式探討。而探討堤前反射率時發現，在2S/L約為0.5的位置時因波浪條件較為非線性，使得能量傳遞至高頻處，而倍頻成分波因為其波長恰落在形成共振的區間，因此使得整體反射率提高。另外也可以發現由於非線性效應的影響使得堤後出現一長波，此結果與Webster & Wehausen（1995）的結果類似，並且在Davies & Heathershaw（1984）中的實驗結果中也可以發現類似的現象。其次，改變潛堤與垂直壁距離的結果可知，佈置垂直壁面時，潛堤後方亦呈現類似駐波的現象，且駐波之振幅變化與壁面和潛堤之距離有關，呈現一週期性變化，峯值間距為L/2，波浪在潛堤與垂直壁面間來回振盪造成能量的累積，這個現象在垂直壁面改為一坡度1：2的斜面進行數值模擬時依然存在，而垂直壁上的波高量測值於某些特定位置時會是原入射波高的數倍以上，因此人工系列潛堤對於海岸的保護性仍然有討論的空間。

Numerical experiments based on multi-layer Boussinesq model developed by Lynett & Liu (2004) were performed to study nonlinear wave propagating over periodic seabed. In particular, one-layer and two-layer models were carried out and the results are compared with experiment data. No visible difference between one-layer and two-layer is found. Furthermore, reflection coefficients due to submerged bars for nonlinear wave are analyzed using three different methods. Amplitude evolution is also presented.
In the case of larger incident waves with no obstacles behind the rippled bed, it is found that nonlinear effects would cause amplitude modulation spatially. This result is identical to the finding of Webster & Wehausen（1995）. In addition, the energy variations for the cases where the vertical wall is set behind the submerged bars are discussed. It is found that the wave amplitude at the vertical wall can be as large as 5 times of the amplitude of the incident wave, indicating that the idea by using artificial periodic bars to protect the shoreline may need further consideration.

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