圆弧型贯底式防波堤防浪效果的解析研究

Analytical research on the sheltering effect on arc-shaped bottom-mounted breakwaters

给出了圆弧型贯底式防波堤防浪效果计算的解析方法。假定防波堤刚性、薄壁、不透浪,水深恒定。假想存在一个圆柱面,把流场划分为内外区域,在每个区域上将速度势用特征函数展开,然后在它们的公共边界上进行匹配,匹配的原则是公共边界上速度连续,压力连续,从而可得到关于未知系数的一组线性代数方程组,解出未知系数,即可求得流域中任意一点的速度势和波高。数值结果给出了不同入射波波长及防波堤所对不同圆心角时防波堤周围波幅的等高线图。结果表明:圆弧型贯底式防波堤具有很好的防浪效果,通常情况下,掩护区域内的波高仅为入射波波高的20%～50%,对于短波,甚至可降到10%。

An analytical method is developed to study the sheltering effect on arc-shaped bottom-mounted breakwaters. The breakwater is assumed to be rigid, thin, impermeable and located in water of constant depth. The fluid domain is divided into two regions by imaginary interface. The velocity potential in each region is expanded by eigenfunctions.By satisfying continuity of pressure and normal velocity across the imaginary fluid interface, a set of linear algebraic equations can be obtained to determine the unknown coefficients for eigenfunctions. Numerical results, in the form of contour maps of the relative wave amplitude around the breakwater, are presented for a range of wave and breakwater parameters. Results show that the arc-shaped bottom-mounted breakwater is generally effective in defending against waves. In general, the wave height in the sheltered area is about 20-50 percent of incident wave height, moreover, 10 percent for the short waves.