The effects of waves on floating bodies are of great importance to the naval architect. In addition to the first order responses to the waves, second order slowly varying forces play a vital role in various scenarios. In this research, a fast and robust method for simulating the drifting of a vessel in a seaway has been developed based on a body-exact strip theory method (cf. Bandyk (2009)). The problem is solved directly in the time domain by setting up a boundary value problem for the perturbation potentials. A boundary integral method is used for solving the Laplace equation. The forces are computed by direct pressure integration. Body accelerations and velocities are computed by using a nonlinear 6-DOF Euler equation of motion solver. Free motion drift simulations have been carried out for long times, on the order of hundreds of wave periods for the Wigley-I hull and the containership S-175. The long time simulations establish the stability and robustness of the numerical scheme. The results also show the effectiveness of the methodology to capture slowly varying 2nd order forces in addition to the wave frequency responses.
The authors take great pleasure in presenting this paper in this symposium honoring Prof. Ronald W. Yeung. Prof. Yeung has worked extensively in the areas of ship hydrodynamics and offshore mechanics. He was one of the first authors to have used a source distribution on the free surface instead of Green’s function to solve time domain free surface problems. The present research work also makes use of a source distribution on the free surface.