RANS investigation of influence of wave steepness on ship motions and added resistance in regular waves

The motions and added resistance of the S175 containership in regular head waves with different wave steepness under the same wavelength are investigated using a Reynolds-averaged Navier-Stokes solver based on a finite-volume method. A level set method is used to capture the free surface and dynamic grids are adopted to simulate ship motions. The variation of heave and pitch motions and added resistance with the wave steepness agrees with the experiment. The higher harmonic components of surge force obtained by the Fourier analysis increase dramatically as the wave steepness increases, while the higher harmonics of heave and pitch are quite small compared to the first harmonics even under large wave steepness. The transient pressure distributions are studied to explain the non-harmonic oscillations of the time history of resistance coefficient. The zeroth, first, and second harmonic amplitudes of pressure are plotted on the hull and the major part of resistance increase in steeper waves is found to be induced at the bow.