Coupling effects on the dynamic response of moored floating platforms for offshore wind energy plants

The increasing importance of offshore deep-water wind energy together with the complexity of the wind-wave-structure interaction problem makes the dynamic analysis of floating platforms a case of considerable interest. In this work, the dynamics of moored floating platforms for deep-water wind energy purposes is analysed in regular waves in order to discuss the effects on the motion due to the coupling of different degrees of freedom, usually associated with the operation of the mooring system and the hydrodynamic action, and the role of the main parameters affecting the motion. The platform is modelled as a rigid body and the associated differential dynamic problem is solved by using a suitable Lie group time integrator. The loads associated with mooring lines and waves are respectively assessed through a quasi-static model and a linear hydrodynamic model. The coupling of different degrees of freedom is usually related to loads with higher-frequency components and non-zero mean value that could bring the system into a mean dynamic configuration rather different from the static equilibrium configuration. Moreover, very interesting to limit the oscillations of the body is the effect of the location of the center of mass, the lower the center the lower the amplitude of pitch and roll response.