Objective Shipborne marine floating-debris interception devices are subject to strong coupling between platform motions and local flexible appendages under wave excitation. Consequently, their hydrodynamic and structural responses are governed not only by global rigid-body motions but also by local load transfer and deformation of the collection structure. To clarify these coupled mechanisms, this study develops a two-way CFD–FEM fluid–structure interaction framework for the hydroelastic analysis of a shipborne marine-debris collection device and applies it to investigate motion responses, wave-induced structural loads, and the effects of key geometric parameters under regular head-wave conditions.

Method A three-dimensional numerical wave tank was established in STAR-CCM+ based on the Reynolds-averaged Navier–Stokes (RANS) equations, the volume of fluid (VOF) method for free-surface capturing, and regular-wave generation techniques. The fluid domain was implicitly coupled with a finite-element structural model of the collection device to realize two-way CFD–FEM fluid–structure interaction. To ensure numerical reliability, grid-independence and time-step-independence studies were conducted prior to the production simulations. The proposed framework was further validated against published hydroelastic experimental data for a benchmark flexible barge by comparing representative motion and load-response indicators. Based on the validated model, systematic parametric simulations were carried out for different wave heights, wavelengths, and device opening angles. Heave and pitch motions, as well as the vertical bending moment and shear force at the root section of the collection device, were analyzed in both the time and frequency domains. In addition, particle-tracking simulations were performed to evaluate debris-guiding behavior and collection efficiency under different structural configurations.

Results The results show that the developed two-way coupling framework can reproduce the principal hydroelastic response characteristics of local flexible marine structures subjected to wave action. As wave height increases, the amplitudes of heave and pitch increase monotonically, while stress concentration at the root connection becomes progressively more pronounced. Under relatively short-wavelength conditions, the vertical bending moment and shear force at the device root are dominated by the fundamental wave-frequency component and exhibit an approximately linear increase with wave height. As wavelength increases, however, higher-order harmonic components become more significant, and the nonlinear characteristics of the hydroelastic response are markedly enhanced. Further analysis indicates that the root connection is the primary load-critical region of the device. In the structural parameter study, increasing the opening angle improves particle guidance and collection efficiency by enlarging the effective interception range, but it also leads to higher vertical bending moments and shear forces at the root section, indicating a clear trade-off between structural safety and collection performance.

Conclusion The proposed two-way CFD–FEM fluid–structure interaction framework provides an effective numerical approach for predicting the hydroelastic behavior of shipborne debris-collection devices in waves. It captures the coupling relationships among wave conditions, global motions, local deformation, and root-section loads, and it offers useful guidance for structural design, opening-angle selection, and safety assessment of ship-mounted marine-debris collection systems.