Empirical formulae of wave loads on quasi-ellipsoid-type foundations surrounded by cylindrical perforated breakwaters

Abstract This study provides empirical formulae of wave loads on quasi-ellipsoid-type foundations coaxially surrounded by perforated breakwaters. The variation of the wave load on each structure versus wave number is characterized as a polygonal line by four key points. The coordinates of these points can be directly obtained from the empirical formulae, which are developed by using mathematical models in the framework of potential theory. The empirical formulae can consider not only the geometric parameters and porous parameters but also the wave exposures and wave numbers. Comparison with the experimental results indicates that the empirical formulae can effectively determine the wave loads on the models under different wave scenarios. Further investigation is conducted on circular foundations, which are the most distinct case of quasi-ellipsoid-type foundations. The wave load magnitudes and phase differences are investigated by experimental and theoretical methods with the consideration of porous parameters and geometric parameters. The experimental results also validate the occurrence of the “phase jump” when the wave loads on the breakwater are minimum. Empirical formulae for the distribution of the “phase jump” points are also presented.