Wave Loads and Ship Motions Evaluated by Linear Strip and Panel Methods

Despite the rapid development of Computational Fluid Dynamics (CFD) the demand for potential flow hydrodynamics in ship design remains relevant. This is because 2D and 3D Boundary Element Methods (BEM) can be applied for rapid prediction of motions and wave loads. This paper compares results from linear 2D strip-theory and 3D Green function methods with empirical forward speed correction factors in terms of ship motions, radiation forces and wave loads. The former approach applies a “Frank Close-fit” method to solve the radiation problem in 2D. The latter utilizes a pulsating “Green function” source distribution method to solve the radiation problem in 3D. Results are validated against experimental data available for a container ship. It is shown that the motion RAOs obtained by both methods are similar and agree with the experimental values. However, responses in terms of longitudinal distribution of wave loads show discrepancies which increase with wave length shortening and closer to the bow region. An increasing role of diffraction and disregarding forward speed wave making affect the results in short waves. Moreover, it is concluded that solving the linear seakeeping problem is not very sensitive to hull form details and to the modelling of forward speed effects on radiation.