Calculation Of Ship Motions And Wave Loads With Maneuverability Effect

The base of the wave load prediction is how to get the reasonable ship motions in waves. However, when the numerical method was used to solve the ship six degree motions in time domain in oblique waves, with the cause of there are no restore forces on horizontal direction, the sway and yaw of ship will diverge with the increasing time step and lead the whole solve process could not run. Based on the three dimensional potential flow theory, the way to add the rudder force and effect into the ship six degree motion equations, and eliminate the divergent components of the ship motions in oblique waves was tried to find in this thesis. For this reason, the following problems were emphatically investigated.Firstly, based on the theory of ship maneuvering motion in waves, the variation of fluid force on the hull caused by maneuvering was investigated, and the time changed function of coupled relation about the rudder force, rudder effect, rudder angle change and wave force on the hull was found.Secondly, under the linear conditions, with the rudder force and moment considered, based on the force equilibrium of the hull, the rudder force and effect was put into the new equilibrium relation with the expression of coefficient matrix, and the new model for the solution of motion and wave load responses of lowly sailing velocity in regular wave was established. The ship motion equations will be solved with the numerical method of fourth-order Runge-Kutta or Hamming in the program of Visual Fortran in time domain.Finally, based on all above the work, the linear six degree motion responses of a container ship in different regular waves were solved by this program. And to certify the program, the results were compared with the results of business hydrodynamics computational software on the same ship.