The accurate generation of a target sea state in numerical or experimental wave tanks is a fundamental line of research for the ocean engineering community. It guarantees the quality and relevance of wave–structure interaction tests. This study presents a reproducible irregular wave generation and qualification procedure, accounting for the nonlinear aspects of wave propagation. It can be used for both numerical simulation and experiments. The presented numerical and experimental results are obtained from the OpenFOAM solver and the Ecole Centrale Nantes wave tank facilities, respectively. The procedure comprises two steps: First, the wavemaker motion is calibrated numerically to generate the target wave spectrum at the position of interest. This is achieved with a wavemaker-equipped nonlinear potential flow solver. The open-source HOS-NWT solver, based on the high-order spectral method, was employed in this study. Then, the corrected wavemaker motion is used directly in the experimental wave tank. OpenFOAM simulations were performed to generate waves with the relaxation method, using wave elevation and velocity field data from HOS-NWT. The procedure was finally tested for mild and extreme breaking sea states. The waves generated by the HOS-NWT solver, the experiment, and the OpenFOAM simulation were compared from both stochastic and deterministic perspectives.

Modeling a nonlinear ocean wave is one of the primary concerns in ocean engineering and naval architecture to perform an accurate numerical study of wave-structure interactions. The high-order spectral (HOS) method, which can simulate nonlinear waves accurately and efficiently, was investigated to see its capability for nonlinear wave generation. An open-source (distributed under the terms of GPLv3) project named "HOS-ocean" was used in the present study. A parametric study on the "HOS-ocean" was performed with three-hour simulations of long-crested ocean waves. The considered sea conditions ranged from sea state 3 to sea state 7. One hundred simulations with fixed computational parameters but different random seeds were conducted to obtain representative results. The influences of HOS computational parameters were investigated using spectral analysis and the distribution of wave crests. The probability distributions of the wave crest were compared with the Rayleigh (first-order), Forristall (second-order), and Huang (empirical formula) distributions. The results verified that the HOS method could simulate the nonlinearity of ocean waves. A set of HOS computational parameters was suggested for the long-crested irregular wave simulation in sea states 3 to 7.

The accurate prediction of ship maneuvering performance is crucial for ensuring maritime safety and operational efficiency. With increasing ship sizes and complex operating conditions, more advanced computational tools are increasingly required. In this study, an OpenFOAM-based in-house solver called foamStar was validated for predicting the hydrodynamic maneuvering behavior of the KRISO Container Ship. A Reynolds-averaged Navier–Stokes equation model combined with a volume-of-fluid approach was employed to capture free-surface effects. A moving mesh method was adopted to solve prescribed ship motions. Simulations were conducted for oblique towing and rotating arm tests under various drift angles and yaw rates, and a mesh convergence study was performed using coarse, medium, and fine meshes. The results showed that the computed sway forces and yaw moments agreed closely with experimental data and numerical benchmarks, and the estimated linear hydrodynamic coefficients closely matched experimental measurements. However, the nonlinear hydrodynamic coefficients require the computations with fine mesh to have similar values with experimental results. In conclusion, foamStar is a reliable tool for accurately predicting hydrodynamic maneuvering coefficients when employing a sufficiently refined mesh.

Wind loads acting on an offshore floating structure are important for the global performance analysis and mooring design. In early design stages, detailed topside geometry may not be fully available; therefore, a wind-load analysis should be performed using simplified geometries. This study investigates the effect of geometric resolution on the wind loads acting on an FPSO using OpenFOAM. A grid sensitivity study was conducted, and the numerical setup was validated against experimental and existing CFD results. Wind-load simulations were then performed using high-, mid-, and low-resolution FPSO geometries. The results show that the mid-resolution geometry, in which pipelines and small topside equipment are removed, showed relative L₂ differences of 2.70%, 3.02%, and 7.78% from the high-resolution geometry for C_Fx, C_Fy, and CMz, respectively.