本文回顾了已有的关于透空式防波堤的波浪透射率的理论计算方法，分析了多层挡板桩基透空式防波堤的消浪机理。结合防波堤断面波浪试验，探讨多层挡板桩基透空式防波堤的消浪特性。研究结果表明多层挡板桩基透空式防波堤能够显著消减波浪，它的应用突破了透空式防波堤仅适用于小尺度风浪水域的经验。研究发现影响防波堤消浪效果的因素中，挡板的透空率和设置方式的影响最为显著。文中提出的减小波浪透射率的方法可供设计部门参考。

简述波浪数值推算的几种模型，对动谱密度平衡方程模型的源项、数值造波和边界条件的处理方法进行研究，在源项中不仅包括非线性四相波相互作用，还引进非线性三相波相互作用，数值模拟波浪在近岸运动机理。与Boussinesq方程和缓坡方程进行了分析比较；数值计算了海安湾有效波高及平均波周期场分布，在非定常情形下以数值试验模拟了计算域内流速和水位变化对风浪要素的影响，讨论了模型将来的发展趋势。

The circumfluence around the Jiuduan Sandbank is thoroughly studied by means of the princi-ple of least resistance in fluid dynamics. The diversion ratio of the North Channel for 1998 is calculated, which is almost the same as the field survey data. The normal and minimum diversion ratios of the North Channel after stages I, [I and I]I regulation works as well as the future phase are obtained. The numerical results and predicted value are accurate.

Based upon the long-term observation of field data, a two-dimensional numerical model is applied to simulating the tidal flow covering from the neap tide to spring nde m the radial sandbank area m the southern Yellow Sea. From the development of tidal current ridges under the hydrodynamic action, multi-purpose analysis and study are carried out, which include the propagation process of tidal wave, the distributions of ndal wave energy rate and tidal range, the tidal ellipses and traces. It is shown that the tidal current is the major dynamm factor for the formation and development of the radial sandbanks, and the differences of tidal wave energy rate and current strength determine the distract plane shapes of ridges and troughs in this region.

In order to study the tidal current ridges, a three-dimensional numerical model is, for the first time, applied to studying the hydrodynamic circumstance with Houbolt's spiral assumption in the rachal sandbank area. It successfully reveals that the radial sandbanks are molded by to-and-fro tidal current as well as the subtransverse circulation current, and that both contribute to maintaining the interior dynamic balance of the sandbanks. It is also found that the subtransverse circulation current would not always appear in pair within the ridges. These discoveries enrich the theoretical results m hydrodynamics of tidal current ridges.