A numerical boundary integral approach is proposed for calculating the diffracted wave fields and hydrodynamic forces resulting from the interaction of firstorder regular waves with a large arbitrary offshore structure. IIi this paper, the structure is assumed to be a rigid body with arbitrary shapes of cross section and the solution is explored by a special boundary integral method based on the use of a complete and non-singular set of functions. The use of non-singular set of complete functions reduces the integral only over the structural surface, resulting in a considerable saving in computational effort. The numerical solutions of wave diffraction problems due to large offshore structures in ocean waves have been presented to illustrate the accuracy and the range of applicability of proposed method and those are found to be satisfactory.
Accurate assessment of wave loads, dynamic pressures and wave-induced sectional forces are essential to optimize the design of offshore structures. With the great increase of interest in offshore structures in recent years, the topic of fluid loading has received considerable attention and a number of reviews and surveys are now available. The problem of wave loading on such structures is highly complex, but it is generally agreed that an important component is due to inertia forces and that these forces are often affected by wave diffraction. When the structure is large compared to the wave length, i.e., if the structure spans a significant portion of a wave length, the incident waves upon arriving at the structure will undergo significantly by scattering or diffraction. In this case the diffraction of waves from the surface of the structure should be considered in the wave-force calculations. The problem was, initially, solved by Havelock (1940) for the deepwater case and extended by MacCamy and Fuchs (1954) for intermediate depths.
