Spar buoy numerical model calibration and verification

The present paper describes the experiences gained from the design methodology and operation of a 3D physical model experiment aimed to investigate the dynamic behavior of a spar buoy (SB) off-shore floating wind turbine (WT) under different wind and wave con-ditions. The physical model tests have been performed at Danish Hydraulic Institute (DHI) off-shore wave basin within the European Union-Hydralab IV Integrated Infrastructure Initiative, in October 2012. The floating WT model has been subjected to a combination of regular and irregular wave attacks and steady wind loads. Observations of hydrodynamics, displacements of the floating structure, wave induced pressures and tensions at critical points of the structure and at the mooring lines have been carried out. Based on the observed data, the numerical model Sesam [1], developed by Det Norske Veritas (DNV), has been calibrated and verified. The adopted numerical model took into account the wave induced response and the effects of the mooring lines on the overall system. The calibration of the numerical model has been performed both for static and dynamic condi-tions. At the end of the calibration procedure, the numerical model has been successfully used to simulate two selected irregular wave attacks.