本文為應用能譜觀念以緩坡方程式所建立之數值模式，由能量通率觀點在方程式中加入能量消散係數，處理非線性淺化效應、碎波效應及非線性波波交互作用求解不規則波浪問題，探討等頻率分割法和混合分割法在處理不規則波浪變形、週期和波譜形狀變化之適切性。並與 SWAN 風浪數值模式之測試結果比較，驗證模式於模擬二維平面不規則波場上之可行性。模式計算結果經與試驗結果比較後得知：混合分割法在處理不規則波浪變形、週期和波譜形狀變化上較等頻率分割法為佳，呈現良好之一致性。基於不失不規則波浪特性及提升計算效率的考量下，選取切割波數為30個時，在模式計算結果上有不錯的表現。

In this study, we apply mild slope equation with spectral method to simulate transformation of irregular waves, and add the energy coefficient into the governing equation in terms of energy flux to deal with nonlinear shoaling、wave breaking and wave-wave interaction. First, divide the significant wave spectrum into different numbers of component waves with different spectral methods. Then we simulate the transformation of irregular waves to investigate equal frequency space and exponential frequency space methods. Meanwhile, the validity of the present model in two-dimensional problem is verified through comparisons with the results of the SWAN model. Comparisons of measured data and numerical results indicate that exponential frequency space wave cutting method is better than equal frequency space wave cutting method. Using exponential frequency space wave cutting method to get 30 component waves has good ability and computational efficiency for simulation of wave height, period and spectrum shape.

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