Wave Forces Acting on a Blunt Ship with Forward Speed in Oblique Sea (3rd Report)

Abstract

A new numerical approach based on the 3-D panel method is presented for the estimation of the wave forces acting on a blunt ship advancing in oblique short waves. Unnatural numerical solutions had been obtained when we applied the 3-D panel method to the wave-making problem of the ship advancing in short waves, and reported comparing with experiments in the 1st report. The reason why the 3-D panel method gives such solutions was not yet made clear, even though some investigations about that problem have been carried out in the 2nd report.In this paper, a new numerical approach has been developed which is free from the aforesaid unnatural solutions. The Spline approximation is effectively applied to the expression not only of the geometry of the ship surface but also of the velocity potential distribution on it, and the integral equation is solved directly with respect to the velocity potential itself instead of the source distribution. Employment of the Spline approximation, moreover, makes it possible to take into account the line integral term and the effect of the steady distrubance on the realistic ship surface.After the numerical test of the present method by comparing with the other results based on the isoparametric approximation or the analytical method, the present method is applied to our wavemaking problem, and it is confirmed that the unnatural solutions can be eliminated perfectly by employing the present method.