Hydrodynamic Response Analysis of a Multi-Moonpool Floating Structure Using the Boundary Element Method

This study aims to evaluate the hydrodynamic response of a displacement-type hull integrated with a multi-moonpool system (one main and sequential cylindrical moonpools) using the Boundary Element Method (BEM), addressing the critical challenge of piston-mode resonance that causes excessive heave motion. The analysis used ANSYS AQWA based on linearized potential-flow theory, assuming infinite water depth and head-sea conditions. Grid independence tests were conducted at resolutions ranging from 5.0 m to 0.7 m, and the resulting Heave RAO curve was benchmarked against a reference dataset. A significant amplitude deviation was found in the high-frequency zone (piston-mode resonance), where the BEM solver overpredicted the heave RAO by 68.77% relative to the reference curve, while both curves showed near-perfect asymptotic alignment in the macro-wave regime. BEM is reliable for predicting motion response in the macro-wave regime, but future hydrodynamic optimization of moonpool structures requires integrating viscous damping modifiers to realistically capture resonance amplitude peaks. Keywords: Boundary element method, Floating structure, Hydrodynamics, Moonpool, Piston mode resonance.