A novel dynamic-modeling framework for assessing the hydrodynamic installation of dynamically installed anchors under combined ocean current and mooring line effects

This study introduces a dynamic model analysis framework to simulate the hydrodynamic installation of dynamically installed anchors (DIAs) under the coupled effects of ocean current and operational mooring lines. The key innovations of this framework lie in its dynamic evaluation of the anchor's directional stability during descent and its integrated treatment of environmental and operational mooring loads. Unlike traditional static approaches, the proposed dynamic model updates the hydrodynamic forces, center of gravity, and applied moment of DIAs at each time step through a six-degree-of-freedom motion calculation module, thereby enabling continuous tracking of the restoration moment coefficient and instantaneous inclination angle. The MoorDyn library, based on the lumped-mass method, is applied to simulate mooring dynamics, and the overset grid technique is employed to facilitate the transfer of information related to fluid–structure interaction. The framework yields critical performance indicators, including directional stability, inclination angle, offset distance, impact velocity, and drag coefficient under the coupling influence of ocean currents and mooring lines. Validation cases confirm the model's robustness and reliability. The verified framework is subsequently applied to investigate the installation characteristics of torpedo- and plate-shaped dynamically installed anchors, with a specific focus on the impact of mooring line configurations and current-line coupling effects on the torpedo anchor performance. Results show that the mooring line reduces the falling velocity of the DIAs and increases their drag coefficient. Current action increases the inclination angle and offset distance of the DIAs, affecting their directional stability. The coupling effect between the two further exacerbates this adverse impact.