Comparative Study of Wave Forces on a Spar-Type FOWT Under Free Floating Conditions: The Role of Slenderness

Renewable energyEnergy, especially offshore wind energyEnergy, has become one of the most rapidly growing energyEnergy alternatives in recent years. Employing offshore wind energyEnergy using a floating offshore wind turbineTurbine (FOWT) can produce more energyEnergy by exploiting large sea areas for installation. Spar-type FOWTs are widely developed due to their simple design and stability compared to other platforms. However, different seawaterSeawater depths in different countries require the spar to be capable of adapting to this. Therefore, this paper aims to explain the effect of slenderness (length over diameter ratio) on wave force considering the six degrees of freedom (6 DOF) of motions. The analysis is performed using the open-source BEM NEMOH software. The reference model is adopted from OC3-Hywind spar-type FOWT. The floater’s geometryGeometry length is varied using ratios of 1.5, 2, 2.5, and 3. The reference volume of OC3-Hywind was used for the floater's diameter. The results indicate that the spar with the largest diameter and shortest floater produces the most significant wave force for translational motion (surge and heave). On the other hand, the spar with the longest floater geometryGeometry and smallest diameter produces the most significant pitch wave force.