Comparative Numerical Study on Focusing Wave Interaction with FPSO-like Structure

Evaluating the interactions between offshore structures and extreme waves plays an essential role for securing the survivability of the structures. For this purpose, various numerical tools—for example, the fully nonlinear potential theory (FNPT), the Navier–Stokes (NS) models, and hybrid approaches combining different numerical models—have been developed and employed. However, there is still great uncertainty over the required level of model fidelity when being applied to a wide range of wave-structure interaction problems. This paper aims to shed some light on this issue with a specific focus on the overall error sourced from wave generation/absorbing techniques and resolving the viscous and turbulent effects, by comparing the performances of three different models, including the quasi-arbitrary Lagrangian Eulerian finite element method (QALE-FEM) based on the FNPT, an in-house two-phase NS model with large-eddy simulation and a hybrid model coupling the QALE-FEM with the OpenFOAM/InterDymFoam, in the cases with a fixed FPSO-like structure under extreme focusing waves. The relative errors of numerical models are defined against the experimental data, which are released after the numerical works have been completed (i.e., a blind test), in terms of the pressure and wave elevations. This paper provides a practical reference for not only choosing an appropriate model in practices but also on developing/optimizing numerical tools for more reliable and robust predications.