In this paper, a Cartesian-grid method is applied to investigate the added resistance of KRISO’s very large crude oil carrier hull with a different bow, particularly in short incident waves. The wavelength is fixed as half of the ship length in all computations. In the present numerical method, a first-order fractional-step method is applied to the velocity–pressure coupling in the fluid domain, and the volume-of-fluid method is adopted to capture the fluid interface. The ship is embedded in a Cartesian grid, and the volume fraction of the ship inside the grid is calculated to identify the different phases in each grid. The sensitivity of the time window during post-processing as well as the number of solution grids is investigated. The computed added resistance is compared with experimental data. In addition, the characteristics of the surge force for different wave amplitudes are observed by comparing the wave elevation around the bow. Further, to compare the relative magnitude of higher harmonic components with respect to the magnitude of the first harmonic component, harmonic analyses of the time history of the surge force are performed. Based on the present numerical results, the effects of the wave amplitude and bow shape on added resistance for a short wavelength are observed. Finally, the distribution characteristics of time-averaged added pressure on the ship surface are investigated for each bow shape and wave amplitude.

This study deals with wave-induced unsteady pressure on a ship moving with a constant forward speed in regular head waves. Two different numerical methods are applied to solve wave–ship interaction problems: a Rankine panel method which adopts velocity potential, and a Cartesian-grid method which solves the momentum and mass conservation equations under the assumption of inviscid and incompressible fluids. Before comparing l1ocal pressure distributions, the computational methods are validated for global quantities, such as ship motion responses and added resistance, by comparison with available experimental data. Then, the computational results and experimental data are compared for hydrodynamic pressure, particularly focusing on the magnitude of the first-harmonic component in different sections and vertical locations. Furthermore, the Cartesian-grid method is used to simulate the various wave-amplitude conditions, and the characteristics of the zeroth-, first-, and second-harmonic components of wave-induced pressure are investigated. The nonlinearity of pressure distribution is observed mostly from the pressure near the still-water-level of the ship bow and the normalized first-harmonic component of wave-induced pressure decreases as the wave steepness increases. Lastly, to understand the local characteristics of wave-induced unsteady pressure, the time-averaged added pressure and added local force are analyzed. It is found that the major contribution of the time-averaged added local force that occurs around the ship stem above the design waterline.