Verification of a new radiation condition for two ships advancing in waves

3-D Rankine source method is used to investigate the hydrodynamic interactions between two ships arranged side by side with forward speed. The radiation condition is satisfied by using a modified Sommerfeld radiation condition which takes into account the Doppler shift of the scattered waves. This new radiation condition is applicable to a wide range of forward speeds, including very low forward speed problem where the parameter τ (τ= uω/. g) is smaller than 0.25. The numerical solution is evaluated by applying the present method to two pairs of models and compared with experimental data and Green function method. Through the comparison study, we verify the new radiation condition and examine the wave patterns for a full range of forward speeds. Discussions are highlighted on the effect of the radiation conditions.