On the estimation method of hydrodynamic forces acting on a very large floating structure. Part 2

Abstract

An estimation method of the hydrodynamic radiation forces on a very large box-shaped floating structure is proposed. This is an extension of a previous paper (Kagemoto H, Fujino M, Zhu T. On the estimation method of hydrodynamic forces acting on a very large floating structure. Applied Ocean Research 1997;19:49–60), in which a diffraction problem was dealt with. In the present paper, radiation problems resulting from forced motions of a very large floating structure including elastic mode of motions are analyzed. By exploiting the fact that, when the horizontal dimension of the corresponding structure is very large, the velocity potential over the bottom surface of the structure has the same spatial distribution as that of the local displacement of the structure, it is shown that the computational burden can be reduced drastically without losing accuracy. As a byproduct of these computations, an interesting feature is found that damping forces acting on the bottom surface of the corresponding structure are very small except near the perimeters of the structure. In order to demonstrate the efficaciousness of the presented methods, the following are analyzed: (a) elastic responses of a very large box-shaped structure in waves; and (b) wave forces on floating airports composed of two runway structures.