PhD Defense - Seung-Yoon HAN - ED SIS

Tuesday 2 April 2024 at 9:30 am at Centrale Nantes, Lecture theatre E

This thesis aims to investigate hydrodynamic loads exerted on heave plates with a focus on the design characteristics of floating wind turbines with a lower submerged depth and a significant motion response compared to conventional offshore platforms. To achieve this goal, extensive experimental campaigns are conducted on a truncated circular cylinder with a heave plate in the hydrodynamic and ocean engineering tank of Ecole Centrale Nantes. The study examines the hydrodynamic loads induced by mono- and bi-chromatic waves, as well as surge, heave, and pitch motions. Various diameters of the plates are studied also considering the porosity and proximity of the free surface across a wide range of flow parameters. Furthermore, a first-order analytical method based on the potential flow theory is developed to solve the wave diffraction and radiation problems. The validation is discussed in comparison with the experimental results and the Boundary Element Method (BEM) solvers. Lastly, dedicated computational fluid dynamics (CFD) simulations are carried out to model the heave plate numerically. It has been confirmed that a turbulence model needs to be implemented through flow visualization. Notably, the results show the presence of strong flow separation around the edge of the plate during the waves and heave oscillations. Consequently, a simplified Morison model is suggested to model the flow separation for the vertical wave diffraction loads.

Supervisor: David LE TOUZÉ

Laboratory: LHEEA