Fully Nonlinear Numerical Simulation About Ship Motion And Load Response Characteristics In Water Of Finite Depth

Nowadays it is of great importance that ships and marine structures in the economic development of morden society.When a ship is being designed,it is necessary to predict the possible wave load and motion response.On the other hand,China has a long coastline with a large number of ports,and the depth of some surrounding waters is shallow.It is necessary to pay attention to the navigation status of ships that sailing or passing in these area.It is becoming a popular technology to simulate the navigation state of ships with the help of professional softwares in the modern ship-design industry.However,most commercial calculation software take infinite water depth as the premise for calculation,due to the particularity of ship navigation state.The simulation of ship navigation state in shallow water is still lacking.Therefore,how to accurately predict the motion and wave load response of the ship under the action of waves in the case of limited water depth has become a research content of great significance.Based on the potential flow theory as well as the fully-nonlinear boundary element method,there is a numerical simulation program realized in FORTRAN language.In this program,the parametric cubic spline interpolation which based on accumulated chord was used,and it was meshed according to the linear interpolation method in order toconstruct the wet surface shape of ship body.After that the fully-nonlinear boundary conditions of the range of fluid area which was selected in advance are defined,including the fully-nonlinear boundary conditions of the body surface,as well as the kinematic boundary conditions,and the dynamic boundary conditions of the free surface.On the other hand,the program of incident wave was realized according to corresponding theory,in order to achieve the desired computing function,which is to simulate the scene that a ship navigating in the water that the depth was limited.As the program was finished,the S175 container ship will be taken as the analysis object to simulate the navigation in several different working conditions,including in water of different depth,or disturbed by waves of different wave length in a specific shallow water state.After that,the fifth-order Stokes wave will be adopted as another kind of incident wave to simulate the navigation similarly.And these simulation result will be compared with the former,in order to analyze the characteristic of ship motion and load response in different water depth or different incident wave conditions.In addition to the calculation and comparison of wave load and motion characteristics between the above wave facing conditions,the zero speed wave response simulation of multiple directions under waves of unit amplitude is also carried out.Through the analysis and comparison of the calculation results,the application effect of the calculation program in oblique wave scenario was tested.