不規則波通過潛堤之變形

Transformation of Irregular Waves Propagating over a Submerged Breakwater

沈茂霖(Mao-Lin Shen) ； 黃清哲(Ching-Jer Huang)

《海洋工程學刊》 7卷2期 (2007/12) Pp. 47-67

https://doi.org/10.6266/JCOE.2007.0702.03

摘要

本文以數值方法求解二維時變的Navier-Stokes方程式及精確的自由液面邊界條件，探討不規則波與潛堤的交互作用。文中應用線性造波理論及定譜振幅模式，造出具有Goda-JONSWAP 譜形的入射波。在確定本模式所造入射波波譜的正確性及可準確重現各成份波之振幅及相位後，本研究有系統地探討不同堤高與堤寬對反射波能量、波譜之演變、流場渦度及渦流的影響。數值結果顯示不規則波通過潛堤時，不僅會產生成份波的二階強制波－次諧波和超諧波，還有波浪交互作用下的能量轉移。

關鍵字

不規則波 ； 潛堤 ； 次諧波 ； 超諧波 ； 反射波能量 ； 渦度 ； 渦流

並列摘要

The unsteady, 2-d Navier-Stokes equations and the fully-nonlinear free surface boundary conditions were solved numerically to investigate the interaction of irregular waves and submerged breakwaters. The deterministic spectral amplitude method performed by fast Fourier transform algorithm was applied to generate the incident irregular waves with the Goda-JONSWAP spectrum. After having verified the accuracy of the incident wave spectrum and the amplitude and phase for each wave component are repeatable, effect of the height and width of breakwater on the reflected wave energy, wave transformation, vorticity and vortex were studied systematically. The numerical results show that propagation of irregular waves over a submerged breakwater produces not only the second order bound waves (subharmonic and superharmonic waves) of the fundamentals waves, but also energy transferring, due to the nonlinear interaction of different wave components in shallow water.

並列關鍵字

irregular waves ； submerged breakwater ； subharmonic ； superharmonic ； reflected wave energy ； vorticity and vortex