A novel frequency-domain optimization method for active absorption wavemaker filters

For physical modeling in coastal and ocean engineering, active absorption is essential to mitigate secondary reflections and maintain the integrity of the target wave field. Active absorption is primarily achieved through the design of frequency-domain filters. This study presents the frequency-domain expressions for the transfer functions of the wave surface in front of the wave paddle and the displacement of the wave paddle under a two-dimensional active absorption mode, and analyzes and processes the low-frequency and high-frequency components. Combining a weighted least-squares algorithm, a filter design scheme based on weighted iterative automatic optimization is proposed. Using the theoretical wave paddle displacement without reflection absorption and the filter-calculated displacement as error metrics, this method automatically designs optimal filters for target operating conditions without manual intervention. To validate the active absorption performance of the proposed filter design algorithm, a two-dimensional frequency-domain active absorption wave-making model was developed based on the Fluent dynamic mesh module and user-defined functions (UDFs). Numerical simulations were conducted for both regular and irregular wave active absorption. The results demonstrate that this method achieves significantly better active absorption performance compared to existing active absorption approaches.