彈性消波板之消波效應

Abstract

本文應用線性元素邊界元素法,結合有限元素法,來解析有關波浪與消波板間之交互作用 的問題.本文所探討 之消波板,包括沒水式平板,出水式水面平板,及嵌入 式海底平板,解析方法 為將整個區域畫分成純流體區及彈性平板區,在純流體區須符和尤拉-白努利樑方程式,依線 性波理論,並配合線性化的動量方程式與邊界條件及交界面之關係條件,再 應用邊界元素法及 有限元素法來解析問題,求得反射係數,透過係數,用來解析彈性消波板對 波浪的影響程度.本 文主要是探討三種不同型態的消波板,分別針對:單一消波板與系列消波板 其消波能力的比較 ,板與板的最佳間距,不同材質的板,及板擺設位置,角度等項,作一分析比 較以瞭解各影響因素對各 消波板消波能力的影響. Boundary element method(BEM) and finite element are developed and combined to study the interaction of linear water waves with a series of elastic plates in water of finite depth.Three types of plates are studied in this thesis:surf- ace pierced plates,fixed floating plates and submerged plates fixed on bottom. The computational domain is divided into two regions,i.e. a water region and a elastic plate region.Based on two dimensional potential flow theory,the water region ismodelling by (BEM) with linear element.The elastic plate is considered as an Euler-Bernoulli beam which is modelling by one dimensional (FEM).Numerica l results show that the reflection and transmission coefficients depend on the characteristic of the elastic plates,the location of elastic plates,the spacing between the plates,the number of plates,and the length of plates.Among these Three types of elastic plates,the surface pierced plates is the best choice to decrease the transmission wave.