Numerical Treatments Of Kelvin Source And Its Application To Ship Wave Problems

The steady motion of ship in calm water is one of fundamental and classic problems in ship hydrodynamics.The wave generated by ship motion and the resulting wave resistance are no doubt important research subjects.In this thesis Neumann-Kelvin theory other than consistent linear mathematic model is adopted.The feature of Neumann-Kelvin is that boundary condition is linearized on free surface,while the precisely hull geometry is retained under the three-dimensional fluid flow.Compared to linear theory,the inconsistent Neumann-Kelvin theory is closer to physics reality.The numerical treatments of Kelvin source and its accurate integration on panel is very important in the calculation of ship wave resistance by means of boundary element methods.The expression of moving point source is given in this thesis.The computation difficulty and treatment method of wave function component is analyzed according to the characteristic of the integrand.The expression of moving horizontal line segment source is deduced based on point source.The high frequency oscillation of the green function is reduced,and the accuracy and efficiency is also improved.According to the space distribution characteristics of the horizontal line segment source,it can be integrated along the vertical direction instead of panel integration.Thus the precision deficiency of the average panel element method is solved.The wave resistance calculation program is developed in this method.The wave resistance,wave profile,sinkage and trim can be given by the program.