Hydroelastic Response Analysis of a Shipborne Marine Debris Collection Device Based on CFD-FEM Coupling

Objectives This study develops a two-way CFD-FEM fluid-structure interaction (FSI) framework for the hydroelastic analysis of a shipborne floating marine-debris collection device. The framework is applied to systematically characterize motion responses and wave-induced loads in regular head waves and to quantify the effects of key structural parameters on nonlinear responses. Methods A three-dimensional numerical wave tank was constructed in STAR-CCM+ and implicitly coupled to a finite-element structural model to achieve two-way FSI. Grid-independence and time-step-independence studies were conducted. The framework was validated against hydroelastic experimental data for a benchmark flexible barge. Under zero-forward-speed regular head-wave conditions, heave and pitch motions, as well as the vertical bending moment and shear force at the device root section, were computed and examined using combined time- and frequency-domain analyses. Results As wave height increased, heave and pitch amplitudes increased monotonically, and stress concentration at the root connection intensified. At shorter wavelengths, the root-section vertical bending moment and shear force were dominated by the fundamental wave component and scaled approximately linearly with wave height. With increasing wavelength, higher-harmonic contributions (second harmonic and above) increased markedly, resulting in enhanced nonlinear behavior. Increasing the opening angle improved debris-guiding performance and collection efficiency, but it also increased the root-section vertical bending moment and shear force. Conclusions The proposed two-way CFD-FEM coupling framework can effectively predict hydroelastic load responses of shipborne collection devices in regular waves and identifies the root connection as the primary load-critical region. For engineering applications, opening-angle selection should balance collection efficiency against structural demand to define an appropriate design range.