Wace Force on Circular Island With Varying Topography based on Perturbation and DRBEM

• Main Authors: Tang, jung-chih, 唐榮志
• Other Authors: Hsiao S.S.
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/05999953125942101919

碩士 === 國立海洋大學 === 河海工程學系 === 85 === In the designs of seawall, harbor and ocean structures, the wave forces areestimated. In order to ensure the safety of the ocean structures under wave forces,the diffraction and refraction in wave are discussed.In the pass years, various numerical models have proposed. Combined boundary element method and perturbation,dual reciprocity boundary element method have been presented.Thetwo numerical methods, one of them with domain integral and the other with great matrix are complex. This paper presents a numerical model combined dual reciprocity boundary element method (DRBEM) and perturbation technique to analyze wave refraction-diffraction around a circular island with the changes in wave forces and wave pressure. In this paper, the analyze domains are seperated into two parts. One for contant water depth,the other one is varying water depth with varying geometry.the governing equation for contant water depth is the mild slope equation. Based on perturbation technics, a homogeneous Helmholtz equation and a non-homogeneous Helmholtz equation can be obtained. The homogeneous Helmholtz equation can be applied on boundary element analysis. The slove equation were substitute into the non-homogeneous Helmholtz equation. Based on the dual reciprocity boundary element method(DRBEM), the integration in the domain is improved. In this paper, combining dual reciprocity boundary element method and perturbation method, the wave diffraction and refraction problems are discussed. The calculated results are compared with those by Homma(1950). Comparisons with those obtained by Poulin(1996) and Rangogni(1988) are conducted, in order to show the applicability of this model. Good agreements are obtained. The model showed to be an adaptable method for solving wave refraction-diffraction problems with varying geometry. In this paper, different topography and wave periods are adopted,in order to discuss the wave forces on circular island with varying geometry.