Motions Added Resistance Of Slender Ship Advancing In Waves

With the deepening manufacturing slump,the shipping industry downturn has lasted for a long period of time.To get through the difficult time and stand out,China’s shipbuilding industry must speed up industrial upgrading.To meet the needs of the society,ships we build should be safer,faster and more comfortable.With the continued deterioration of the environment,energy saving and emission reduction has become the common voice of the whole world,IMO calls for the implementation of "new shipbuilding energy efficiency design index"(EEDI)after 2013,more environmentally friendly..As the key part of EEDI,Fw is mainly related to the added resistance of ships advancing in waves.Accordingly,finding the most suitable method to calculate the forces ships subject to and predict ship motions and added resistance in waves,become a top priority.It means a lot to the ship designing and building work.Considering the current situation of domestic and foreign research,Frequency Domain Method is more mature,compared with Time Domain Method and CFD Method,the strip method is widely used in engineering practice.But with the speeds of ships go up,The speed effect of free surface becomes remarkable,the strip method is not capable to give sufficiently accurate results.The high-speed slender body theory and three dimensional potential flow theory will become the next step to give ship motion prediction for engineering practice.However,3D translating & pulsating source method is too time-consuming and not able to give stable results for certain types of ships.That leaves us the high-speed slender body theory and 3D pulsating source method.To compare the applicability of this two methods,the hydrodynamic problem of two ships was solved and analyzed by using this two methods,which is very important for the engineering application.Compared with other methods to calculation the added wave resistance of ships,radiation energy method shows better agreement with experimental values,investigation on the two dimensional semi method combining with the radiation energy method to calculate the wave resistance has both the research significance and the important engineering application value.First,the development of potential flow theory was-discussed in detail,the solution procedure and numerical methods for several frequency domain problems were introduced.By means of frequency domain method and time domain method,a two dimensional problem were solved.The correctness of the Green’s function in time domain was verified at the same time.By discussing methods for improving the accuracy of numerical integration,the choice of the integral method was determined.Then,the paper completed the WIGLEYIII hydrodynamic forces calculation and motion prediction by using high-speed slender body theory and speed correction method separately.In the application of high-speed slender body theory for calculation of hydrodynamic force,and the numerical simulation and comparison of two kinds of hydrodynamic calculation methods were carried out.At the same time,both high-speed slender body theory and Speed Correction Method were adopted to predict the motions of Wigley III under two navigation conditions.The accuracy and efficiency of these two methods for the prediction of ship motion in waves at a given speed were studied,by comparing their results with test results.Next,the paper established a method that based on high-speed slender body theory combined with radiation energy method,to solve the wave added resistance of ships.Then use this method and the method of speed correction method with radiation energy method to calculate the added resistance in waves of Wigley III and S175.By comparing the results of these methods with the results of the experiment,the conclusion of the applicability of the two methods was-obtained.At last,the paper summarized all the work,conclusions of the comparisons of these two methods were given,and suggestions were made for future research.All the work of the paper were done by programming in FORTRAN language.It has been proved that the software developed in this paper is stable and universal by using it to calculate motions and added resistance of Wigley III ship model and S175 ship.