Numerical analysis to consider effect of zigzag floating breakwater geometry on its performance

In this paper, a new concept of the floating breakwater with zigzag geometry on the seaside of the floating breakwater body was studied numerically. The hydrodynamic analysis of the zigzag floating breakwater has been investigated using the boundary element method based on the three-dimensional diffraction radiation theory. The zigzag floating breakwater was designed by deforming the seaside wall of the breakwater with three different zigzag angles (60, 90, and 120 degrees). The numerical model was validated against experimental data from a pontoon-type breakwater, demonstrating strong agreement with a root mean square error (RMSE) of 0.093 for the transmission coefficient. The RMSE values for sway, heave, and roll response amplitude operators were 0.28, 0.20, and 0.34, respectively, confirming the reliability of the model. The results revealed that the zigzag geometry significantly increases turbulence within the wave field, disrupting typical wave reflection patterns and enhancing energy dissipation due to the greater upstream surface area of the breakwater compared to conventional straight breakwaters. Notably, the 90° zigzag configuration with a middle heave plate exhibited superior performance, achieving a transmission coefficient of 0.28 at w²B/2g = 0.8, compared to 0.84 for a conventional rectangular breakwater. At higher frequencies (w²B/2 g ≥ 1.1), the 90° zigzag breakwater with a heave plate further outperformed other designs, achieving a Ct of 0.15 at w²B/2 g = 1.43, compared to 0.44 for the rectangular breakwater. The inclusion of the heave plate was found to enhance performance for mid-range wave conditions but had minimal impact during longer wave periods. For shorter wave periods, the zigzag design demonstrated significant advantages over traditional configurations, particularly in reducing wave transmission.