Numerical Computation of Water Tranquility in a Harbor

• Main Authors: San-xue Chen, 陳聖學
• Other Authors: J.R.C. Hsu
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/19001065748156328278

碩士 === 國立中山大學 === 海洋環境及工程學系研究所 === 92 === Harbor construction is the most important basic development in fishery. To sustain harbor tranquility and prevent entrance from siltation are essential for maintaining normal operations of a harbor. Although the number of fishing harbors in Taiwan is said to be as many as the car parks on the land, there are numerous reports of poor tranquility that required urgent public attention. Supported by recent development in science and technology, research advances in numerical modeling have produced accurate results from a range of numerical schemes. Comparing to the conventional hydraulic models that require long executive time and large budget, numerical modeling on computer is a most effective alternative. In this study, the wave analysis system－CATWAVES developed by Professor Shigeaki Tsutsui at University of the Ryukyu in Okinawa, Japan is adopted to simulate the wave motions around a fishing harbor, in order to evaluate the tranquility of a harbor basin. CATWAVES calculates the transformation of surface gravity waves in the ocean using a mild-sloped equation of elliptic type. A finite-element scheme is used effectively to handle arbitrary bottom bathymetry and irregular boundary. This report first provides an outlines of the CATWAVES system, followed by verification of wave height distribution for two classic cases, being waves passing a semi-infinite breakwater in constant depth and waves propagating over a submerged circular shoal on a sloping beach, respectively. The CATWAVES system is then applied to assess the harbor tranquility at two prototype fishing harbors in Taiwan. The first case is to verify the results of several improvement options tested in hydraulic models elsewhere to improve the tranquility at Badoutz, a class one fishing harbor in northeastern Taiwan. The second case is to provide a better alternative plan of breakwater extension at Mito, a class three harbor in the southwestern part of Taiwan, where excessive wave heights have been experienced by local fishermen. It is believed that Tsutsui’s CATWAVES system has made a great breakthrough in handling irregular bottom bathymetry and arbitrary outline of harbor plan. From the two prototype cases examined in this study, this system is found to be highly adaptive for calculating wave motions around any fishing harbor in Taiwan.