斜向入射波浪與系列透水潛堤的交互作用

Abstract

本文根據線性波理論，採用線性元素的邊界元素法，解析固定水深的水平底床內， 斜向入射波浪與系列透水潛堤的交互作用的問題。問題的領域劃分成純流體區及 可透水潛堤區，純流體區滿足勢能流理論;可透水潛堤區滿足 {\rm Sollitt and Cross(1972)}提出的擬勢能流理論，配合線性化的邊界條件 及交界面關係，求出反射係數以及透過係數。 從單列透水潛堤開始，給定不同的入射波波長、入射角度以及不同的潛堤形狀;雙列 及三列透水潛堤則給定不同的堤頂寬度、潛堤間距、入射角度、潛堤高度，探討 這些條件對反射係數、透過係數的影響。 數值計算結果發現影響單列透水潛堤消波效能的因素，依重要性分別為：潛堤 堤頂高、潛堤寬、波浪入射角度、及堤側坡度。雙列以上的透水潛堤則還有間距 的因素。再則最小透過率和最大反射率並沒有對應同一個相對水深，在其他條件固定， 增加入射角的條件下，增加潛堤間距不一定會提高消波效果。

Base on a two dimensional linear water wave theory ,this work develops the boundary element method (BEM) with linear element to examine the interaction of oblique water waves with a series of submerged permeable breakwaters. In this study , the flow field is separated into two regions: a pure water region and a porous structure regionPotential throry is applied to the pure water region,and the pore velocity potential theory of Sollitt and Cross is applied to the porous structure region.Numerical results for reflection,transmission and energy dissipation will be provided.The reflection and transmission coefficients of water wave are effected by the incident angle of wave,the height of breakwater , the shape of breakwater,the width of breakwater and the clearance between each breakwaters.The numerical technique's accuracy is confirmed by comparing the numerical results with previously numerical and experimental ones of the interaction of waves with single submerged permeable breakwater.