NONLINEAR EFFECTS ON HIGH BLOCK SHIP AT LOW AND MODERATE SPEED

A Rankine panel method is used for the solution of the fully nonlinear free surface problem, in particular for high block ships (CB greater than 0.75). High block ships usually have a blunt bow and hence experience extreme waves with huge crests followed by deep troughs near the bow region. These phenomena are nonlinear. A new algorithm has been developed, consisting of a nested pair of two iterative procedures: an inner and outer iteration. The inner iteration is to solve the system of nonlinear equations that results from eliminating the unknown wave height from the kinematic and dynamic free surface conditions on the current (outer) free surface. The outer iteration is conducted on the free surface determined from the converged solution of the previous inner iteration. Singularities are distributed on the actual wetted ship hull and the updated free surface location obtained during the outer iteration. The previously reported one parameter family of advection methods is also used. The computation for Series 60 with block coefficient 0.80 and Model B at various speeds successfully reveal the details of wave profiles at the bow, hull, and stern. The computational results illustrate the stability, efficiency and accuracy of this approach for all tested hull forms and speeds.