Experimental study on the wave attenuation performance of a floating breakwater under oblique irregular waves and wave–current interaction conditions

This study employed physical model experiments based on a practical engineering project to investigate the wave attenuation performance of a floating breakwater under oblique irregular wave and wave–current interaction conditions. The effects of key controlling parameters, including wave incident angle, relative water depth, wave steepness, relative width, and relative current velocity, on the transmission coefficient (Kt) were systematically analyzed. The results indicate that the floating breakwater used in this engineering project exhibits satisfactory wave attenuation performance under oblique irregular wave conditions, with both transmitted wave heights and the occurrence probability of high wave crest events on the lee side being significantly reduced. The transmission coefficient Kt exhibits pronounced nonlinear responses to the governing parameters. As the relative water depth increases, Kt shows an overall increasing trend, with an inflection point occurring at a relative water depth of 4.5, beyond which the growth rate increases markedly. With increasing wave steepness, Kt rises significantly. In contrast, increasing relative width leads to a pronounced reduction in Kt, with an accelerated decreasing trend. Meanwhile, Kt generally decreases with increasing wave incident angle, and the most favorable wave attenuation performance is observed under the 45°condition. Under wave–current interaction, Kt exhibits an overall decreasing trend with increasing relative current velocity. Relative contribution analysis based on the investigated experimental parameter ranges reveals that relative width is the dominant controlling factor, contributing 42.9% to the variation in Kt, followed by relative current velocity and wave incident angle, whereas relative water depth has the smallest influence. This study elucidates the dominant control mechanisms and governing factors affecting the wave attenuation performance of floating breakwaters under oblique irregular wave and wave–current interaction conditions through physical model experiments, and provides a quantitative basis for parameter optimization and layout design in practical engineering applications.