Computations of fully nonlinear three-dimensional wave-wave and wave-body interactions. Part 2. Nonlinear waves and forces on a body

The mixed-Eulerian-Lagrangian method using high-order boundary elements, de scribed in Xue et al. (2001) for the simulation of fully nonlinear three-di mensional wave-wave and wave-body interactions, is here extended and applie d to the study of two nonlinear three-dimensional wave-body problems: (a) t he development of bow waves on an advancing ship; and (b) the steep wave di ffraction and nonlinear high-harmonic loads on a surface-piercing vertical cylinder. For (a), we obtain convergent steady-state bow wave profiles for a flared wedge, and the Wigley and Series 60 hulls. We compare our predicti ons with experimental measurements and find good agreement. It is shown tha t upstream influence, typically not accounted for in quasi-two-dimensional theory, plays an important role in bow wave prediction even for fine bows. For (b), the primary interest is in the higher-harmonic 'ringing' excitatio ns observed and quantified in experiments. From simulations, we obtain full y nonlinear steady-state force histories on the cylinder in incident Stokes waves. Fourier analysis of such histories provides accurate predictions of harmonic loads for which excellent comparisons to experiments are obtained even at third order. This confirms that 'ringing' excitations are directly a result of nonlinear wave diffraction.