A Method to Predict Free Surface Flow Around Ship by Means of Rankine sources

Abstract

This paper describes a numerical method for solving free surface flow around ship. The velocity potential is expressed as a sum of the basic velocity potential of double model flow and the perturbed wavy potential. The perturbation potential is solved using Rankine sources which are distributed on the hull surface and the undisturbed free surface. The method of solution is based on the iteration procedure to satisfy the hull surface condition and the double model linearized free surface condition. The method of numerical calculation is examined on the flow around a two dimensional submerged circular cylinder and three dimensional mathematical hull form. The effectiveness of successive approximations is examined, and it is found that the solution of 2nd approximation is required to satisfy the boundary condition on general hull form. Further, the wave profile, pressure distribution on the hull surface and wave resistance that is obtained by integration of pressure on the hull surface are calculated, and good agreement with experimental results are obtained. Finally, from the view point of practical use, this method is applied to predict wave resistance of full ship in ballast condition, and the effect of bow bulb on free surface flow and wave resistance is discussed in comparing with experiment.