Oblique wave interaction with a floating dock in the presence of inverted trapezoidal pile-rock breakwaters

Abstract

This study evaluates the performance of a pair of inverted trapezoidal pile-rock breakwaters (PRB) placed at a finite distance from the floating dock and connected to a partially reflecting seawall under the oblique wave incidence. The PRB consists of pile shields to protect the rock core from the displacements due to incident wave stroke. The porous boundary conditions, such as continuity of pressure and velocity, are incorporated between the breakwater and open water regions. The multi-domain boundary element method (MBEM) is used to evaluate the breakwater performance against the incident waves under the small amplitude wave theory assumption. Before analyzing the proposed breakwater system, the validation of study results is presented for specific structural configurations to strengthen the accuracy of the proposed results. The proposed non-identical inverted trapezoidal breakwaters of ascending heights, D1/h = 0.6 (seaside) and D2/h = 0.8 (shoreside) installed at a finite spacing with 40% porosity to minimize wave loads and to obtain well-balanced scattering and force coefficients. It shows peak energy damping of 92% for a porosity of 40%, which is 56% higher energy dissipation relative to the trapezoidal breakwater of comparable bulk with the same porosity, and it depicts the minimum moment on the floating dock for the extensive part of relative water depths. The harmonic peaks of higher magnitude are observed in the scattering and force coefficients against the relative spacing, with maximum (97%) wave energy dissipation and minimal (0.2) force coefficients for the escalated heights (D1 = D2 = 0.9h) of the inverted trapezoidal breakwaters.