Abstract
Research on multi-body hydrodynamics is of major importance within the field of ocean engineering, and it is facing rapid development mainly due to the latest technologies in Offshore Renewable Energies and Very Large Floating Structures. Given the high level of complexity intrinsic to those systems, it also faces a need for efficient analysis methodologies. In this paper, an efficient time-domain model suitable for multi-body floating structures is developed based on Cummins formulation and multi-body hydrodynamics theory, where the convolution terms are replaced by a state space model, greatly improving the calculation efficiency, also coupled with a lumped-mass dynamic mooring model. The hydrodynamic behaviour of a hinged double barge is used for verification. Then, the model is applied to a semi-submersible floating wind turbine coupled with surge flaps. It is found that the proposed model has a high level of accuracy with computational efficiency one order of magnitude higher than another state-of-the-art method. It is also demonstrated that, the hybrid platform presents higher motion amplitudes in surge, heave and pitch in the low frequency wave band when compared to the stand-alone floating wind turbine in the surge and pitch DOF, also, that a significant amount of wave energy is absorbed near the flaps’ natural frequencies.