Large Amplitude Body Motion Computations in the Time-Domain

Large amplitude, time-domain, wave-body interactions are studied in this paper for problems with forward speed. Both two-dimensional strip theory and three-dimensional computational methods are shown and compared by a number of numerical simulations. In the present approach, an exact body boundary condition and linearized free surface boundary conditions are used. By distributing desingularized sources above the calm water surface and using constant-strength flat panels on the exact body surface, the boundary integral equations are solved numerically at each time step. Once the fluid velocities on the free surface are computed, the free surface elevation and potential are updated by integrating the free surface boundary conditions. After each time step, the body surface and free surface are regrided due to the instantaneous changing wetted body geometry. The desingularized source method applied on the free surface produces non-singular kernels in the integral equations by moving the fundamental singularities a small distance outside of the fluid domain. Constant-strength flat panels are used to model bodies with any arbitrary shape. Extensive results are presented to validate the efficiency of the present methods. These results include the added mass and damping computations for a modified Wigley hull and a S-175 hull with forward speed using both two-dimensional and three-dimensional approaches. Heave force and pitch moment time histories of a S-175 hull due to a heave motion using a time-domain body-exact strip theory are presented. Diffraction forces acting on a modified Wigley hull due to a linear head sea incoming wave using fully three-dimensional method are also obtained. All the computational results are compared with experiments or other numerical solutions.

Presented at the International Conference on Numerical Ship Hydrodynamics (9th) held in Ann Arbor, Michigan, on August 5-8, 2007. Published in the proceedings of the conference (unnumbered pages), 2007. The original document contains color images. This article is from ADA495720 International Conference on Numerical Ship Hydrodynamics (9th) held in Ann Arbor, Michigan, on August 5-8, 2007