Here we consider the case of a train of linear water waves incident on a bottom-mounted surface-piercing compound partial-porous cylinder consisting of two coaxial cylinders of which the upper cylinder is hollow with a thin porous side wall and the lower cylinder, with radius greater than that of the upper one, is rigid. Subsequently, we examine the associated hydrodynamic forces. Using linear water wave theory and eigenfunction expansion, the problem is developed in terms of suitable velocity potentials. The important boundary condition on the porous boundary is defined with the aid of Darcy’s law. The matching conditions across the linear interface between successive fluid domains arising due the continuity of pressure and velocity are suitably used. Thereafter, a system of linear equations arises in terms of the unknowns solving which the hydrodynamic force and wave run-up for the compound partial-porous cylinder are calculated. Various numerical experiments show the effect of different parameters, such as porosity of the upper cylinder, draft ratio, the ratio of radii of the upper and lower cylinders and the depth of water on hydrodynamic force and wave run-up. It is observed that the wave force takes higher values corresponding to lower values of radius ratio, draft and porous coefficients. Further, for fixed values of radii, porosity and depth, the wave run-up is observed to be more when the wavenumber takes increasing values. The obtained results establish that different parameters may be suitably chosen in order to design useful ocean structures which may be installed as wave-absorbers for various activities in ocean including capturing of wave energy. Further, such structures can also act as the base of windmills installed in oceans to extract wind energy. The efficiency of the model developed is validated by comparing it with an available established result from which an excellent agreement is observed.

在这里，我们考虑一列线性水波入射到底部安装的表面穿孔复合部分多孔圆柱体上的情况，该圆柱体由两个同轴圆柱体组成，其上部圆柱体是空心的，带有薄的多孔侧壁，下部圆柱体是半径大于上部的半径，是刚性的。随后，我们检查了相关的水动力。利用线性水波理论和本征函数展开，根据合适的速度势发展了该问题。借助达西定律定义了多孔边界上的重要边界条件。适当地使用由于压力和速度的连续性而产生的连续流体域之间的线性界面上的匹配条件。之后，根据未知数产生了一个线性方程组，该未知数求解可计算出复合部分孔圆柱体的流体动力和波浪上升。各种数值实验表明，上圆柱体的孔隙率，牵伸比，上，下圆柱体的半径比以及水深对水动力和波浪上升等参数的影响。可以看出，波浪力取较高的值，对应于半径比，拔模系数和多孔系数的较低值。此外，对于半径，孔隙率和深度的固定值，当波数采用增加的值时，观察到波上升更多。获得的结果表明，可以适当地选择不同的参数，以便设计有用的海洋结构，该结构可以作为吸波器安装用于海洋中的各种活动，包括捕获波能。此外，这种结构还可以用作安装在海洋中以提取风能的风车的基础。通过将模型与可获得的既定结果进行比较来验证所开发模型的效率，从中可以观察到极好的一致性。