THE DESIGN OF HULL FORM USING COMPUTER SYSTEM FOR ANALYSIS OF SHIP FLOW

The paper presents a computer system executable on personal computers for the determination of flow parameters of a ship with or without a propeller. The system is based on a potential solution of the three-dimensional flow around the hull, taking into account the free water surface. The basis of solution is determination of the distribution of Rankine type singularities on the double hull surface discretized by a number of flat panels. After solving the linear boundary condition on the free surface the system of Bernoulli waves is calculated. The system of ship generated waves is obtained thorough a transformation of the Bernoulli waves. This transformation is based on an original solution of the Green function for a single pressure pulse and an equally original method of superposition of such solutions, leading to a very short computation time. The wave resistance is then calculated through integration of pressure on the hull taking into account the deformed water surface. The propeller is modelled by lifting surface theory and its interaction with the ship is taken into account by including propeller induced velocity in the boundary condition on the hull. The propeller loading is determined by evaluation of total resistance, thrust deduction and wake fraction using a procedure based on simple theoretical and empirical relations. The system enables the determination of wave resistance, wave profile on waterline, streamlines and pressure distribution on the hull surface, and wave system on the free surface, for a ship model moving with constant speed in calm water. The results of calculations are presented graphically on a computer screen, on a printer or on a plotter. The paper describes the theoretical model, structure of the computer system and graphical presentation of the results. The results are presented for a modern, medium size container ship.