Two-dimensional analysis on the lateral drifting force between two floating structures.

An analytical procedure for evaluating the lateral drifting forces between two structures by the near field method is presented. The velocity potentials, including the hydrodynamic interactions were evaluated by a two dimensional sink source technique. This method yields the mean drifting force consisting of four components of which the relative wave elevation term is dominant, whereas the Bernoulli quadratic term is secondary. The phenomena of negative drifting force was found in the study, which are consistent with the standing wave or negative added mass. The near field method clearly reveals the effects of the behaviour of the response motions such as heave and roll resonances, although it seems to be complicated at first and difficult to use. It was also found that the hydrodynamic interactions between two bodies cannot be neglected. The near field solutions are required for the further analysis of the quadratic frequency responses function in order to obtain the non-linear (second order) interaction effects in the presence of dual waves. (A)