Abstract
This study investigates the hydrodynamic characteristics of single-layer heave plates with varying salient edges and triple-layer configurations with size mismatches under forced oscillation, utilizing 3D overset mesh numerical simulations. For single-layer plates, the 0° edge configuration maintains high hydrodynamic coefficients across all conditions, whereas the 135° edge peaks under specific parameters. Introducing horizontal gaps consistently degrades performance. For triple-layer plates, increasing the spacing ratio mitigates spatial flow interference, significantly enhancing hydrodynamic coefficients. Furthermore, introducing size differences creates a stepped mismatched configuration that effectively mitigates wake shielding and enhances fluid entrainment. Consequently, the coefficients increase steadily with the absolute size difference, reaching optimal heave suppression in the triple-layer arrangement with a large spacing and a ±20 m size mismatch. Finally, a highly accurate empirical formula (R2 > 0.92) is proposed to predict the damping (Cd) and added mass (Ca) coefficients, effectively capturing the nonlinear coupling effects of spacing ratio and size difference. These findings provide practical theoretical guidance for optimizing vibration reduction systems in offshore platforms.