Application of Genetic Algorithm for Optimum Hydrodynamic Performance of Twin Pontoon Floating Breakwater

Abstract

The lateral separation ratio (S/D) between the twin pontoons of a floating breakwater (TPFB) is one of the prominent factors that attenuate wave energy transmission and reflection. In fact, a numerical investigation of optimum TPFB S/D is inevitably required. To accommodate such a requirement, a numerical optimization model of a genetic algorithm (GA) was developed to assess the optimum S/D primarily through minimizing wave transmission (Kt) and reflection coefficients (Kr) while maximizing the energy dissipation coefficient (Kd). Several parameters, such as wavelengths and S/D ratios including a set of optimization criteria, were taken into account in the simulation, where the optimum solution was then selected from various populations. In addition to the current GA simulation, the optimum S/D was evaluated and quantified by the values of Kt, Kr, and Kd, in which the reduction of some flow parameters was visualized via computational fluid dynamics. The results revealed that the GA simulation is effectively capable of determining global trade-offs between Kt, Kr, and Kd. As compared with the existing model, Kt and Kr decreased to less than 0.3 and 0.4, respectively, whereas Kd increased up to 0.9, resulting in optimum TPFB hydrodynamic performance. Hence, the elaboration of this optimization algorithm can serve as a conceptual design to find an optimum S/D for the twin pontoons of a floating breakwater.