A New Approach for Long Wave Attenuation of Floating Breakwater: Mechanism and Validation

Floating breakwaters have attracted considerable attention due to their environmental friendliness. However, their effectiveness in attenuating long-period waves remains limited. To address this challenge, this study proposes a novel approach to enhance long-wave attenuation by leveraging the added mass generated by radiation motions. The effects of added mass and damping on the transmission coefficients of a square-box floating breakwater were investigated, and their relationships were derived using an analytical formulation. Results showed that increasing the heave added mass significantly improves the breakwater’s performance in attenuating long-period waves. Based on this mechanism, a new breakwater configuration is proposed, and a series of high-fidelity numerical simulations were conducted to comprehensively evaluate its wave attenuation capability and motion response. The results confirm that the proposed configuration markedly improves wave attenuation in long-period conditions, highlighting the critical role of added mass in performance enhancement. Compared to traditional single-box floating breakwaters, the new design demonstrated a 30% increase in wave-absorbing efficiency. Furthermore, this configuration was implemented in an engineering-scale floating breakwater project within a designated sea area to mitigate long-period wave impacts. To ensure its effectiveness and safety in practical applications, a series of physical model tests were carried out. The tests demonstrated that the breakwater achieved over 65% wave attenuation for wave periods ranging from 5.5 to 12.0 s. The findings of this study provide valuable insights for the design and development of floating breakwaters suitable for long-wave conditions.