波浪作用下方箱-水平板浮式防波堤时域水动力分析

在线性化势流理论范围内求解方箱-水平板浮式防波堤的波浪绕射和辐射问题,从时域角度分析了浮式防波堤的水动力特性.采用格林函数法将速度势定解问题的控制微分方程变换成边界上的积分方程进行数值求解,浮式防波堤的运动方程采用四阶Runge-Kutta方法求解.对不同层数水平板的浮式防波堤的波浪透射系数、运动响应和锚链受力进行了计算分析,结果表明方箱相对宽度对方箱-水平板浮式防波堤的波浪透射作用有重要的影响,透射系数随着方箱相对宽度的增加而减小.对于方箱加二层水平板的浮式防波堤,在本研究的计算条件下,当方箱相对宽度从0.110增加至0.295时,透射系数从0.88减小至0.30.水平板有利于增加浮式防波堤对波浪的衰减作用,但随着水平板层数从0增加至2,这种波浪衰减作用增加的程度趋弱.方箱-水平板的浮式防波堤的运动量小于单一方箱防波堤的运动量.与此对应,方箱-水平板防波堤的锚链受力小于单一方箱防波堤的锚链受力.

Timedomain hydrodynamics analysis of pontoonplate floating breakwater under waves actions

A mathematical model is developed based on the linear potential theory to solve the wave diffraction and radiation problem of the floating breakwater. The hydrodynamic properties of the breakwater consisting of a rectangular floating pontoon and horizontal plates are investigated in time domain. The solution for the fluid motion is obtained by the boundary integral equation method using a simple Green＇ s function in time domain. The motion equations of the floating breakwater are solved by the fourth order RungeKutta method. The numerical results of the wave transmission coefficient, the motion responses of the floating breakwater with different layers of horizontal plate and the mooring forces are presented. The results show that the relative width of the pontoon has an important influence on the wave transmitting effect of the pontoonplate floating breakwater. The transmission coefficient decreases with the increase of the relative width of the pontoon. For the pontoon floating breakwater with two horizontal plates, the transmission coefficient decreases from 0.88 to 0.30 as the relative width of the pontoon increases from 0.110 to 0. 295. The horizontal plates conduce to promote the wave attenuating effect of the floating breakwater. However, as the layer of horizontal plate increases from 0 to 2, the increasing effect of wave attenuation by the floating breakwater becomes weak. The motion responses of the pontoon floating breakwater with plates are less than those of single pontoon floating breakwater. Corresponding to the motions, the mooring force of the floating breakwater with plates is less than that of single pontoon floating breakwater.