OC6 Phase Ia: CFD Simulations of the Free-Decay Motion of the DeepCwind Semisubmersible

Currently, the design of floating offshore wind systems is primarily based on mid-fidelity models with empirical drag forces. The tuning model coefficients requires data from either experiments or high-fidelity simulations. As part OC6 (Offshore Code Comparison Collaboration, Continued, Correlation, and unCertainty (OC6) a project under International Energy Agency Wind Task 30 framework) project, present investigation explores latter option. A verification validation study computational fluid dynamics (CFD) DeepCwind semisubmersible undergoing free-decay motion performed. Several institutions provided CFD results for against experimental campaign. objective to evaluate whether setups participants can provide valid estimates hydrodynamic damping needed by models. linear quadratic equivalent ratio are chosen as metrics validation. Large numerical uncertainties estimated coefficients; however, ratios more consistently predicted lower uncertainty. Some difference observed between surge-decay motion, which caused mechanical not considered in simulations that likely originated mooring setup, including Coulomb-friction-type force. Overall, experiment show reasonable agreement, thus demonstrating feasibility using tune