In the present study, the effectiveness of using multiple slatted screens placed in front of a caisson porous breakwater to dissipate the incident wave energy is analyzed. To model the water flow through the slatted screens, a quadratic (nonlinear) pressure drop condition which involves both the inertial and drag effects is considered. Further, for thick porous structure, the well known Sollitt and Cross (1972) model is used. To handle the nonlinear boundary conditions, an iterative multi-domain boundary element method (BEM) is used. The numerical convergence of the multi-domain BEM based solutions is presented. Energy identities for flow past a single slatted screen, multiple slatted screens and for the present problem are derived. The study shows that the minimum reflection coefficient ($<1\%$) and maximum wave energy dissipation ($>98\%$) can be obtained by using four slatted screens. Further, for moderate values of perforation-effect Keulegan-Carpenter number ($KC$), the reflection coefficient attains maximum for ${\displaystyle \frac{b_1}{\lambda }\approx \frac{n}{2},}$ $n=1,2,3,\cdots$ ($b_1$ is the distance between the rigid caisson and the front slatted screen, $\lambda$ is the incident wavelength) irrespective of the variations in the number of slatted screens. Further, the transmission coefficient, horizontal and vertical wave forces acting on the rigid caisson attain maximum for $b_1/\lambda \approx 0.55n,$ and minimum occurs for ${\displaystyle \frac{2n+1}{4}<\frac{b_1}{\lambda }<\frac{3n+2}{6},}$ $n=0,1,2,3,\cdots$. The Bragg resonance in the reflection coefficient occurs at Bragg value $\approx 1.6$ irrespective of the variations of $KC$ number. Moreover, the reflection coefficient increases around the Bragg value for higher values of $KC$ number without altering the peak value in the reflection coefficient.

在本研究中，分析了使用放置在沉箱多孔防波堤前面的多个板条式筛网消散入射波能量的有效性。为了模拟流过板条筛的水流，考虑了涉及惯性和阻力效应的二次（非线性）压降条件。此外，对于厚的多孔结构，使用众所周知的Sollitt and Cross（1972）模型。为了处理非线性边界条件，使用了迭代的多域边界元方法（BEM）。提出了基于多域BEM的解决方案的数值收敛性。推导了流过单个板条筛，多个板条筛的流体的能量标识以及当前问题。研究表明，最小反射系数（$<\mathrm{1个}％$）和最大波能耗散（$>98％$）可以通过使用四个板条式屏幕来获得。此外，对于中等程度的射孔效应，Keulegan-Carpenter数（$ķC$），反射系数达到最大值 ${\displaystyle \frac{b_{\mathrm{1个}}}{\lambda }\approx \frac{ñ}{\mathrm{2个}}，}$ $ñ=\mathrm{1个}，\mathrm{2个}，3，\cdots$ （$b_{\mathrm{1个}}$ 是刚性沉箱与前条板筛之间的距离， $\lambda$是入射波长），与板条式屏幕的数量变化无关。此外，作用于刚性沉箱的传递系数，水平和垂直波力在$b_{\mathrm{1个}}/\lambda \approx 0.55ñ，$ 最小发生 ${\displaystyle \frac{\mathrm{2个}ñ+\mathrm{1个}}{4}<\frac{b_{\mathrm{1个}}}{\lambda }<\frac{3ñ+\mathrm{2个}}{6}，}$ $ñ=0，\mathrm{1个}，\mathrm{2个}，3，\cdots$。反射系数的布拉格共振发生在布拉格值$\approx 1.6$ 不论...的变化 $ķC$数字。此外，对于较高的值，反射系数在布拉格值附近增加$ķC$ 数量而不改变反射系数的峰值。