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 survivabilityof 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 andemployed. However, there is still great uncertainty over the required level of model fidelity when being applied to a widerange of wave-structure interaction problems. This paper aims to shed some light on this issue with a specific focus on theoverall error sourced from wave generation/absorbing techniques and resolving the viscous and turbulent effects, by comparingthe 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 couplingthe QALE-FEM with the OpenFOAM/InterDymFoam, in the cases with a fixed FPSO-like structure under extreme focusingwaves. The relative errors of numerical models are defined against the experimental data, which are released after thenumerical works have been completed (i.e., a blind test), in terms of the pressure and wave elevations. This paper providesa practical reference for not only choosing an appropriate model in practices but also on developing/optimizing numericaltools for more reliable and robust predications.