Numerical analysis of floating structures for off-shore and harbour engineering

The aim of the research was to create an open source numerical model able to simulate every kind of harbour and offshore structure, fixed and floating. The code implemented was able to reproduce a physical wave tank and can be used during the design phase as an integration to physical tests. OpenFOAM was used as a starting point to develop the new code, furthermore the boundary condition IHFOAM tool was applied to generate and absorb waves. In order to reproduce deep water conditions, the code was improved with new boundary conditions and a new turbulent model. Furthermore an additional numerical restraint was implemented in the solver interDyMFOAM for representing a realistic mooring line when simulating floating structure with OpenFOAM. The new numerical tool was calibrated and validated thanks to a comparison with experimental tests. Furthermore, the way to generate coupled waves and currents was explained and shown. Results of all the tests carried out were promising; showing good agreement with theoretical values and physical tests. An application to a real study case was finally shown; a floating wind turbine was designed for an offshore area in Mazara del Vallo, (Sicily, Italy) and its response to wave loads was analysed with the new code. The real case application demonstrated the model can be helpful in the design phase and it can be used for a wide range of applications, from harbour floating piers to offshore structures. Moreover, this methodology, with active absorption, lead to reduce the domain covered by the 3-D model and to simulate the interaction between sea states and structures in competitive times and computational costs.