A Higher-Order Panel Method Based On NURBS For The Ship Radiation Problem With Forward Speed

Compared with the theoretical and experimental methods, numerical method has some merits in predicting ship hydrodynamic performances. Since 1960's, with the development of computer science and technology, many breakthroughs have been obtained on the Computational Fluid Dynamics (CFD). The application of CFD in resolving ship hydrodynamic problems results in a new branch in ship hydrodynamics — ship CFD. As ship CFD is more and more widely used in engineering problems, accurate and rapid solution of ship hydrodynamic problems by potential theory method becomes more and more important. One of the focuses of recent researches is to solve the ship hydrodynamic problems using higher-order panel method. In recent years, many higher-order panel methods have been proposed, and among them the higher-order panel method based on the Non-Uniform Rational B-Splines (NURBS) is most promising due to its merits that it can be combined with the Computer Aided Design (CAD) and conveniently used in ship design from the point of view of ship hydrodynamic performances.In this thesis, a higher-order panel method based on NURBS has been developed for computing the hydrodynamic coefficients of a ship undergoing a forward motion and an oscillating motion of small amplitude, with the free surface effects being taken into account. Rankine source is employed as the Green function, and NURBS is used to describe the body geometry and the distribution of the source strength. The free surface boundary conditions are linearized so that the boundary-value problem is formulated and solved in frequency domain. The proposed method can be used to simulate the flow of captive model tests by PMM to determine the hydrodynamic coefficients with high accuracy and efficiency.The proposed method is firstly applied to calculate the added mass of a sphere and spheroids moving in unbounded fluid. The numerical results are compared with the theoretical ones to check the validity of the proposed method. Then the method is used to solve the radiation problem with forward speed effects for a submerged spheroid and a Wigley mathematical model of surface ship. The numerical results ofhydrodynamic coefficients for 2nd and 6th mode of ship motion are presented and discussed. Some conclusions are drawn from the analysis of the computation practice and the numerical results.