Wave Damping and Refraction-Diffraction Due to Variable Depth Porous Bottom

作     者：朱书堂 

作者机构：Institute of Nuclear Energy TechnologyTsinghua UniversityBeijing 100084China 

出 版 物：《Tsinghua Science and Technology》 (清华大学学报（自然科学版（英文版）)

年 卷 期：2004年第9卷第2期

页      面：138-147页

核心收录：

学科分类：080103[工学-流体力学] 08[工学] 080104[工学-工程力学] 081502[工学-水力学及河流动力学] 0815[工学-水利工程] 0801[工学-力学（可授工学、理学学位）] 

基　　金：Supported by the"85"Foundation of Tsinghua University(No.092213005) 

主　　题：porous breakwater potential theory wave-damping wave refraction-diffraction 

摘      要：The refraction-diffraction of surface waves due to porous variable depth has been the subject of many investigations. In the present study, we extend the boundary-value problem of impermeable varying topography to that of a variable depth porous seabed, which is the situation most likely to be encountered in practical prob-lems of coastal engineering. A wave-induced fluid motion is applied to the porous bottom, while the well-known linear potential theory is applied to the free-water above the bottom. Eigenfunction expansions are employed to derive the matching condition and the so-called modified dispersion relation. As a result of the porous bottom, the wavenumber becomes a complex value, of which the real part represents the spatial periodicity while the imagi-nary part refers to the energy dissipation. The characteristics of water waves over a porous bottom are studied in detail. By neglecting the non-propagating modes which only have a local effect and damp exponentially with dis-tance, we derive a mathematical model to represent the characteristics of both the wave refraction-diffraction and wave-damping. The developed model is applied to the damping problem of waves over submerged porous breakwaters.