Three-dimensional solutions of exciting forces between two ships in waves

In the paper, a three-dimensional potential-flow theory is adopted to analyze the diffraction problem between two moving ships in waves. The hydrodynamic interactions between two ships including the speed effect are considered. Basically the general formulations are based on the source distribution technique, by which each ship hull surface is regarded as the assembly of many panels. Using the series expansions of Telste & Noblesse algorithm for the Cauchy principal value integral of unsteady flow, the corresponding Green functions and their derivatives can be easily solved numerically. Two pairs of models are used for calculations, and comparisons with experimental data and strip theory are made. The hydrodynamic interactions are found to be important generally. But it is also found that the hydrodynamic interaction calculated by 3D method is not so significant as that by 2D method in the resonance region, which is physically reasonable and improves the predictions. The present study offers an efficient tool, which is not very complicated but more reliable, to predict the exciting forces between two moving ships and can be taken as a good basis to analyze the problems of underway replenishment at sea.