Numerical Calculation Of Wave-making Resistance On Ships Moving In Restricted Water

With the speed and scale of modern ships getting higher and larger, the depth turns shallow and the width turns narrow correspondingly, which made the sea-route be the restricted water. When the ship moves in the above-mentioned route, the bottom and bank sides exert much influence on the wave-making resistance. In order to design the high-speed ship moving in the restricted water, it is meaningful to research the effect of the width on the resistance.A Rankine Panel Method is developed for calculating the nonlinear wave-making resistance of a ship moving forward with a constant speed in restricted water. Based on the potential theory, the disturbance velocity potential is expressed by a Rankine source distribution on the body surface, the free surface and the bank sides. The nonlinear free surface condition is satisfied in an iterative manner, whereas the boundary condition on the bottom is satisfied by the method of images, and the radiation condition is satisfied by the numerical technique of staggered grids. That is to say, the free surface source layer is elevated to a certain height above the free surface and the panel sources are replaced by the point sources, which are shifted backwards relative to the collocation points on the free surface in the longitudinal direction. The source strength are obtained by satisfying all the boundary conditions on each side, and the wave-making resistance is gained consequently.Using the above-mentioned method, this thesis made numerical calculations for a mathematical hull Wigley. The wave-making resistances of the ship moving in deep water were calculated out, and the results are closed to the data published in the literatures, which test the reliability of the program. The results in shallow water were obtained at different speeds and with different widths in the waterways, then the effect of the width on the resistance was analyzed and some meaningful conclusions were drawn. According to the curve gained from theresults of this thesis, some references can be offered about the decision of the befitting size of the ship models.Because the most actual bank sides are slantwise, the wave-making resistance under different width conditions was calculated by changing the angle of the bank sides to test the practicability of this program. By analyzing the angle of the slantwise bank and the coefficient of the wave-making resistance, the optimal distance to the bank can be determined.The research of the thesis is helpful to the prediction for hydrodynamic performance of the ship and the guidance for ship model experimentation.