潛堤目前已經廣泛的用於海岸的保護上，潛堤設置的用意為提早破壞波浪結構及消散波力與能量，減少波浪對海岸的直接衝擊，進而達到保護灘線與維護自然景觀的目的；然而當潛堤的材質為可透水時(如：碎石防波堤)，因孔隙介質會提供流經之流體額外的摩擦力，所以其削減效果優於不透水潛堤。近來人造多孔結構物(如: 碎石防波堤、人工魚礁、海堤的護甲層)已引起海岸工程界廣泛的興趣與討論，由於實際海面是不規則的，所以正確的呈現不規則波浪與潛沒透水結構物的互制現象是工程設計時相當重要的課題。本計畫為兩年期計畫，第一年(目前執行中，97.08.01~98.07.31)所欲探討的問題為開發線性及非線性不規則波數值造波模式，用以探討不規則波浪的頻譜特性(如：譜寬參數、水深…等)對不規則波列側頻不穩定現象之影響，並輔以座標轉換的技巧，研究不規則波列與任意形狀之不透水潛沒結構物的互制作用。本計畫第二年 (98.08.01~99.07.31)所欲探討的問題為將第一年發展完成的模式與多孔介質的模式結合，並引入座標轉換，探討不規則波列與任意形狀之透水潛沒結構物的互制作用。 Submerged breakwaters are widely used for coastal protection against wave attack. The goal of this kind of structure is to reduce the transmitted wave energy by reflecting the waves and dissipating the incident wave energy by breaking up the waves. When the structure is made of porous material, such as a rubble-mound breakwater, additional wave energy is dissipated due to the flow friction within the porous media. Recently, artificial porous structures such as rubble-mound breakwaters and artificial fishing reefs or armor layers for the protection of seawalls have received great interest in coastal and harbor engineering. Natural, sea waves will be irregular, with stochastically varying wave heights and periods. An accurate representation of the submerged permeable structure response under irregular wave attack is of prime importance for engineering design purposes. The main purpose of the present project in the first year (this project is carries out now, 97.08.01~98.07.31) is to develop a numerical linear and nonlinear random wave tank and using this numerical tank to investigate the interaction between random wave trains and submerged impermeable structures. The influence of the spectrum bandwidth and water depth on the stability of random wave trains also will be discussed in the first year. The main purpose of the present project in the second year (98.08.01~99.07.31) is to develop a numerical model and using this numerical model to investigate the interaction between random wave trains and submerged permeable structures.
