Development of a Time-Domain Rankine Source Method for Hydrodynamic Interaction Analysis of Adjacent Floating Bodies

This study develops a time-domain Rankine source method for predicting wave loads and motion responses of adjacent floating bodies. The method combines desingularized Rankine source nodes on the free surface with an acceleration potential formulation to improve the stability of time-domain simulations. The boundary-value problem is formulated using an indirect boundary integral equation method, and the hydrodynamic forces are coupled with the equations of motion. The developed code is validated through convergence tests and comparisons with the experimental data, 3D HOBEM results used as comparison solutions, and HydroStar results for two adjacent barges. The computed wave-exciting forces and motion RAOs reproduce the overall frequency-dependent trends and dominant response characteristics of the reference results. The simulations show that gap flow and shielding effects strongly govern the hydrodynamic interaction between adjacent bodies. In beam seas, the weather-side barge generally experiences larger loads and motions, whereas the lee-side barge is shielded in the short-wave region. Under oblique waves, three-dimensional wave interaction produces a more complex load distribution. Parametric studies show that the separation distance changes the frequency range of gap-flow-induced responses, while shallow water shifts the main resonance toward lower frequencies and modifies the response magnitude. These results demonstrate the applicability of the present method to closely spaced floating systems.