Abstract
This study examines the hydrodynamic performance of multiple-row vertical slotted breakwaters. We developed a mathematical model based on an eigenfunction expansion method and a least squares technique for Stokes second-order waves. The numerical results obtained for limiting cases of double-row and triple-row walls are in good agreement with results of previous studies and experimental results. Comparisons with experimental measurements of the reflection, transmission, and dissipation coefficients (C-R, C-T, and C-E) for double-row walls show that the proposed mathematical model adequately reproduces most of the important features. We found that for double-row walls, the C-R increases with increasing wave number, kd, and with a decreasing permeable wall part, dm. The C-T follows the opposite trend. The C-E slowly increases with an increasing kd for lower kd values, reaches a maximum, and then decreases again. In addition, an increasing porosity of dm would significantly decrease the C-R, while increasing the C-T. At lower values of kd, a decreasing porosity increases the C-E, but for high values of kd, a decreasing porosity reduces the C-E. The numerical results indicate that, for triple-row walls, the effect of the arrangement of the chamber widths on hydrodynamic characteristics is not significant, except when kd< 0.5. Double-row slotted breakwaters may exhibit a good wave-absorbing performance at kd> 0.5, where by the horizontal wave force may be smaller than that of a single wall. On the other hand, the difference between double-row and triple-row vertical slotted breakwaters is marginal.