The Applications Of High-order Boundary Element Method To The Ship-Generated Waves

A high-order boundary element method(BEM) based on potential flow theory has been applied to solve the ship waves and its effects on structures. The thesis includes the evaluations of the Green function in the theory of steady motion of a ship, waves generated by a steady-moving ship, ship waves'effects on various structures such as fixed structures, floating structures and the floating collar of the gravity cage. The thesis is organized as follows:A comparison is made among three different numerical methods:direct integral method, modified integral method and series approximation. The times occupied by direct and modified integral methods are compared with each other, and the range of application for series approximation is further evaluated.A Kelvin source with high-order boundary element method is developed to solve the wave-making problems. This model developed in the present thesis can be applied to the linear wave-making problems of arbitrary bodies. The results for ship waves in various speeds, distances away from the ship are presented and compared with experimental results.The diffraction of simple shape bodies is examined by comparing wave forces with the frequency-domain results, constant BEM and high-order BEM. The diffraction problems of fixed structures under ship waves are further considered. The relationships of ship speed, ship length, ship beam and ship draft with wave forces induced by ship waves are numerically analyzed.Then, diffraction-radiation problems of simple shape bodies are examined and compared with the results of frequency-domain method, constant BEM and high-order BEM. The relationships of ship speed, ship length, ship beam and ship draft with wave forces and motion responses of floating bodies by ship waves are further discussed.In the final application, the forces on the floating collar of gravity cages using Morison equation are numerically simulated. The parameter analyses of ship speed, distance between ship and structures, ship length, and ship beam with the forces by ship waves are also carried out.