A Study on the Propagation of Oblique Incident Wave Past a Thin Barrier by Using the Dual BEM

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Project title

Code/計畫編號

NSC89-2211-E019-022

Translated Name/計畫中文名

潛堤對斜向入射波消波影響之對偶邊界元素法分析

Project Coordinator/計畫主持人

Jeng-Tzong Chen

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Harbor and River Engineering

Website

https://www.grb.gov.tw/search/planDetail?id=581408

Year

2000

Start date/計畫起

01-08-2000

Expected Completion/計畫迄

31-07-2001

Bugetid/研究經費

514千元

ResearchField/研究領域

土木水利工程

本計畫為研究含剛性邊界條件之潛堤承受斜向入射波消波功能，採用對偶邊界元素法來分析擺置潛堤對波浪所造成的影響。於分析時，將奇異積分方程(UT式)及超奇異積分方程(LM式)之奇異積分(Singular integral)與超奇異積分(Hypersingular integral)轉換成正規積分(Regular integral)。為了驗證所建構的對偶積分方程的正確性，發展一套解斜向入射問題的對偶邊界元素程式。藉由此程式可得知流場的變化，計算出反射係數(Reflection coefficient)與穿透係數(Transmission coefficient)從而知道潛堤的消能效果，解決傳統邊界元素法於對退化邊界所造成解的不唯一之問題。最後並以實例比較本法、解析解、有限元素法與實驗所得的數值結果，驗證本法的可行性。 In this report, the dual integral formulation for the modified Helmholtz equation in solving the propagation of oblique incident wave passing a thin barrier (a degenerate boundary) is derived. All the improper integrals for the kernel functions in the dual integral equations are reformulated into regular integrals by integrating by parts and are calculated by means of the Gaussian quadrature rule. The jump properties for the single layer potential, double layer potential and their directional derivatives are examined and the potential distributions are shown. To demonstrate the validity of the present formulation, the transmission and reflection coeffcients of oblique incident wave passing a thin rigid barrier are determined by the developed dual BEM program. Also, the results are obtained for the cases of wave scattering by a rigid barrier with a zero thickness in a constant water depth and are compared with those of experiment and analytical solution using eigenfunction expansion method. Good agreement is made.

Keyword(s)

潛堤
斜向入射波
消能效率
對偶邊界元素法
反射係數
Submerged dike
Oblique incident wave
Energy dissipation efficiency
Dual boundary element method
Reflection coefficient

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A Study on the Propagation of Oblique Incident Wave Past a Thin Barrier by Using the Dual BEM

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