High-efficiency multiscale SPH modeling of ship-wave impact jetting as the hydrodynamic source of sea spray

Sea spray icing presents a significant hazard to polar navigation, yet accurate prediction remains challenging because of the limited understanding of the initial generation mechanisms. While wind influences the subsequent transport of droplets, the initial ejection velocity and volume are governed primarily by the hydrodynamics of ship-wave impact. Accurately capturing this source requires balancing the high resolution needed to model nonlinear free-surface breakup with computational efficiency constraints. To bridge this gap, this study develops a high-efficiency multiscale model for ship-wave impact jetting within weakly compressible Smoothed Particle Hydrodynamics (WCSPH). By integrating a domain decomposition strategy with the modified Dynamic Boundary Condition (mDBC) and advanced Particle Shifting Technique (PST), the resolution around a representative polar ship is locally refined to capture the jet hydrodynamics accurately. Compared with a uniform high-resolution SPH model, the proposed model reduces the computation time by 86.9%. The validation against experimental towing tank data demonstrates the prediction accuracy, with maximum relative errors for the jet height and impact pressure at the monitoring point limited to 6.89% and 3.03%, respectively. A parametric investigation reveals that spray generation is governed by a complex, nonmonotonic mechanism interplay between sea spray and green water. Analysis of the spatial distribution indicates that, although the bluffer bow increases the total spray volume, it paradoxically reduces centerline accumulation by shifting the jet origin outward. These findings elucidate the hydrodynamic mechanisms responsible for sea spray generation and provide a robust quantitative tool for optimising the layout of anti-icing equipment.