A practical nonlinear method for calculating ship wavemaking and wave resistance

This paper presents a new method, developed at the Maritime Research Institute Netherlands, for predicting the wave pattern and wave resistance of a ship. A panel method is used to calculate the steady potential flow satisfying the fully nonlinear free-surface boundary conditions. A particular feature is the use of the source panels at a distance above the free surface. This has several practical advantages, but, as is shown analytically and numerically, also results in a quite accurate representation of surface waves. An iterative procedure is adopted to cope with the nonlinearity and free-surface character of the problem. The convergence problems typical of earlier methods seem not to occur with this method. Usually, 4 to 15 iterations are sufficient, making this approach most efficient. The computer program RAPID (RAised Panel Iterative Dawson) is now being introduced in commercial ship design work.

The paper describes the basic decisions leading to the approach followed, outlines the method, and describes accuracy and sensitivity analyses. A few applications are shown stressing the importance of nonlinear effects.