V形防波堤与圆弧型防波堤之浅水波绕射作用的比较

Comparison of shallow water wave diffracted effects caused by a V-shaped breakwater and arc-shaped breakwater

应用椭圆余弦波的绕射理论,推导了V形防波堤的浅水波浪绕射解析解,从而对现有的Airy微幅波理论进行了有效拓展。据此理论对V形防波堤的浅水波绕射作用进行了解析计算,并与几何形状相近的圆弧型防波堤结果加以了对比。结果表明:椭圆余弦波理论计算的V形防波堤最大波浪力和最大绕射波面明显大于微幅波理论的对应值。本方法适用于张角180°的有限长直立薄壁防波堤的浅水波绕射作用计算,从而将无限长直立薄壁堤的反射波理论加以有效拓展。张角同为120°的V形堤与圆弧堤的堤后防浪效果相近,而180°圆弧堤的堤后防浪效果优于张角90°的V形堤。

The theoretical solutions to shallow water wave diffraction by a V-shaped breakwater are derived with the use of cnoidal wave theory,the current Airy small-amplitude wave theory.Based on that,theoretically measure the impact on V-shaped breakwater that diffracted shallow water.The results show that,under the same shallow water conditions,the maximum dimensionless wave forces and wave surfaces on the V-shaped breakwater are larger than those predicted by the small-amplitude wave theory.The method given in the paper is suitable for calculating diffracted wave effects with the breakwater angle 180°on the finite length vertical thin-walled breakwater.The diffracted effects of a 120°V-shaped breakwater and a 120°arc-shaped breakwater are similar and a 180°arc-shaped breakwater diffracted effect is greater than that of a 90°V-shaped breakwater.