Time-domain calculation of moored ship motions in nonlinear waves

Numerical modelling of moored ship behaviour in a harbour requires an accurate description of the harbour geometry and bathymetry for a correspondingly accurate determination of the associated wave phenomena diffraction, refraction and reflection. On a smaller scale an accurate description of the 3D shape of the ship is required to determine the wave forces on the ship. These requirements are difficult to combine in a single model, so that a combination of a Boussinesq-type wave model with a time-domain panel model is developed and described in this paper. With this approach it is possible to determine the wave forces on a moored ship including the contributions of second-order waves and harbour oscillations and second-order drift forces. The model is validated against model tests for the wave forces due to a passing ship and further results are presented for a ship in irregular short-crested waves.