Extension of the free-surface Green's function multipole expansion for the infinite water depth case

This paper presents new developments on the multipole expansion of the infinite water depth free-surface Green’s function, in the scope of wave farm simulation. The multipole expansion of the Green’s function and its derivatives have been extended to be used in a 3D fast multipole algorithm. Previous restrictions over the use of the multipole expansion are proven to be unnecessary. Extensive validation is provided by evaluating this function over a large range of parameters. The influence of the fast multipole algorithm parameters on the accuracy of the multipole expansion and on the CPU time are then investigated.