Performance evaluation of Spar equipped with solitary and double heave plate for use in east coast of India

Numerical techniques which are effective and affordable can be used to model and solve complex situations in ocean engineering problems. Either the time domain or the frequency domain can be used to solve the fluid structure interaction problems involving regular and random waves. The ANSYS AQWA program which is built on three-dimensional panel method which falls under the category of Boundary Element Method is designed to analyze the interaction between surface waves and offshore structures using diffraction radiation phenomenon. Heave plates have been extensively employed on Spar as dampening mechanisms to minimize its motion responses. These plates are effective in offering viscous damping and considerable added mass in heave mode. This hybrid approach began with 1:100 scale free-decay tests of the Spar, run both bare-hulled and with a damping plate fitted, to capture its physical heave behaviour. The resulting hydrodynamic response of the Spar carrying twin heave plates was then simulated under regular and irregular sea states in ANSYS AQWA, a potential-flow-based solver. Because AQWA cannot capture viscous effects on its own, the gap between the total damping measured experimentally and the radiation damping predicted numerically was treated as non-linear viscous damping and fed back into the model as an external user-defined input. The role of relative spacing on Spar’s motion response was assessed and subsequently presented in the analysis. The simulated results revealed that the Spar featuring a pair of heave plates with a relative spacing ranging from 30 to 40% greater than that of Spar integrated with a solitary heave plate possessing a diameter ratio of 1.3 was highly effective in reducing responses under both regular and random wave conditions. The adoption of motion-reduction technologies in these platforms facilitates the development of clean energy solutions, thereby contributing to the achievement of United Nations Sustainable Development Goals on affordable and clean energy.