Wave-making Hydrodynamic Forces Acting on a Ship with Drift Angle and Wave Pattern in Her Neighborhood

Abstract

The numerical method to the new slender ship theory is described for calculating the flow around a slender ship with a steady drift angle. The study of this paper is in only the wave-making problem. The method of representing the ship by sources distributed over the surface of the hull is utilized here, and the densities are determined by solving Volterra integral equation of the second kind on the basis of the approximate hull boundary condition due to the assumption of the slender body. The velocities are directly obtained from numerical differentiation of the total velocity potential in three axis directions. Then, wave-making resistance, lateral force and yaw moment acting on the ship at various Froude numbers are computed by integrating pressure on the hull surface. In order to investigate the relationship between the ship wave change and the drift angle, the wave patterns are calculated for several drift angles. All above calculations are based on the marching integration, so it is seen that such a numerical procedure is in a sense efficient to numerical ship hydrodynamics. The Wigley model is used in the present calculation. From the comparison of calculated and measured ship waves, the pratical application of the theory is examined further.