Comparison of Different Soil and Hydrodynamic Force Models on a 13.2MW Offshore Rotor

The present work highlights differences between two soil models (the classical p-y curves and a FEM based super element model) and two hydrodynamic force models (the classical Morison approach and the more complex Rainey slender body force models). The paper highlights the differences between the models, focusing on the effect on the total fatigue experimented by the rotor on a reduced load matrix. A monopile for a 13.2 MW rotor was designed in the stiff-soft region and fully aeroservo-elastic simulations were run using the aero-servo-hydro-elastic tool 3DFloat. Results show conservative prediction of loads given by the PY curves, leading to a possible conservative design and increase of the overall amount of steel used. As for the hydrodynamic loads models, the Rainey and the Morison model gave identical results when provided with linear wave kinematics.