Drift Forces On A Floating Or Submerged Spherical Structure By Multipole Expansion Method
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A theoretical investigation about the drift forces on a spherical structure in waves of a finite depth ocean has been presented in this paper. We have used the linearised potential theory to obtain the velocity potential by use of the multipole expansion methods with the help of a Green function. The solution contains terms of an infinite series of associated Legendre functions with unknown coefficients. The series expression for the second order mean forces (drift forces), is provided by integrating the fluid pressure over the body surface. When the body is surface-piercing, in addition to the hydrodynamic drift forces, there exists the waterline drift forces. We are presently working on this problem to obtain analytical and numerical calculations. This study should be treated as a preliminary step forward for more complex investigation of offshore engineering problems.