A Nonlinear Hydroelastic Interaction of Floating Bridges under Shallow-Water Waves over Irregular Seabeds

Abstract Floating bridges in coastal regions are subject to complex hydroelastic interactions driven by variable seabed topography and inhomogeneous wave fields. Traditional potential flow and Boussinesq models often lack accuracy in these shallow-water environments due to their inability to fully resolve nonlinear wave transformations and seabed-induced dispersion. To address this, we present a novel time-domain hydroelastic framework coupling a fully nonlinear non-hydrostatic wave model (NHWAVE) with a Rankine source potential-flow solver. The NHWAVE module resolves determining nonlinear wave evolution and pressure fields over irregular bottoms, while the Rankine source method efficiently computes radiation and diffraction effects in the frequency domain, accounting for arbitrary seabed geometries. The system is solved in the time domain using Cummins’theory. Validation against single-body and multi-body cases demonstrates that this coupled approach significantly outperforms standard methods in capturing nonlinear drift forces and complex wave-structure interactions over varying depths.