High-fidelity Simulation of Offshore Crane OperationUsing Smoothed Particle Hydrodynamics

For floating crane / heavy lift operations, precisely determining the coupled motion behavior of the crane vessel and crane load is essential for a safe and efficient offshore crane operation. This determination is usually achieved using numerical and/or analytical models. Most of these models rely on data from potential flow theory. However, these data neglect viscous effects, which may be significant depending on wave conditions, hull shape, and other external factors. A CFD model that solves the Navier-Stokes equations is necessary to incorporate these viscous effects into numerical simulations fully. However, mesh-based CFD models require special treatment of moving structures, particularly in cases involving large motions. While the mesh-based simulation of simple floating structures has been exhibited in various examples, the simulation of crane vessel and crane load poses a difficult challenge for mesh-based models due to the possible large motion of the crane load, e.g., during the lowering of the load. Hence, meshless simulation approaches like the smoothed particle method pose a valid alternative for such types of simulations. In the present study, the meshless numerical model DualSPHysics is employed to simulate the coupled motion of the crane load and the crane vessel under two different wave conditions. Firstly, the simulation results are compared with experimental and numerical data for a 9D configuration, which includes a crane vessel with 6 degrees of freedom and a crane load modeled as a point mass with 3 degrees of freedom. This comparison highlights the suitability of the employed numerical model for simulating offshore crane operations with a reasonable computational cost and sufficient accuracy. Finally, the capabilities of the numerical model regarding transient offshore operations, i.e., lowering of a crane load, are presented. Although this type of application is theoretically possible, further implementations are necessary to extend DualSPHysics into a productive tool for such applications.