Application Of Planar FEM In 2-D Potential Fluid Problems

When running in wave, ships generate complex motion because of perturbations of wave. The complex motion can be divided into six motions including rolling, pitching, yawing and surging when the ship act a rigid body, swaying, heaving. It's very critical of obtaining the hydrodynamic coefficients. Many people have studied and investigated the added mass and damping coefficients of hull before, but different people obtained different results. So, it's meaningful to do more research.Generally speaking, there are three methods for these questions, boundary element method, conformal mapping method and finite element method. But not many person uses finite element method.Based on planar finite element method, this article is to analyze and study the two dementional hydrodynamic problems including circling fluid around cylinder section and radiative potential function on heaving section. This article solve wave motion equations by finite element method and program by FORTRAN coding. Because the added mass and damping coefficients of hull can be got through integrations of the added mass and damping coefficients of two-dimension section, so in this article the results are added mass and damping coefficients of the section. Then the numerical solutions of added mass and damping coefficients are obtained. To show the function of the method in this article, simulation of circling fluid around cylinder section is done, and the result is satisfied. Comparisons to results from other methods are done. The results are also compared with each other. Finally, this article study the circling fluid around some heaving section.Comparisons to results from other methods show that the calculation in this article is precise enough. All of our work proves that planar finited element method is efficient in the calculation on hydrodynamic problems. So the method in this article can be used to solve difficult problems in marine engineering.