Session: 09-01-10 Wind Energy: Moorings 2

Paper Number: 127684

127684 - An Upgraded Direct Forcing Immersed Boundary Method With Integrated Mooring Algorithm for Floating Offshore Wind Turbines 

An upgraded direct forcing immersed boundary method is implemented in the open-source hydrodynamic framework REEF3D::CFD for simulating the six-degrees-of-freedom (6DOF) motions of a floating offshore wind turbine (FOWT) based on the OC5 semi-submersible design. The direct forcing method is enhanced with a new density interpolation method across the fluid-structure interface that removes unphysical spurious phenomena and ensures stable and accurate wave load calculations on floating objects. A quasi-static algorithm is used for modelling the mooring system of the OC5 platform and restraining its motions in waves. The Navier-Stokes equations are solved on a staggered structured rectilinear grid for the hydrodynamic simulations. The level-set method is used to capture the free surface of the ocean waves. A ray-casting algorithm is employed to get inside-outside information near the fluid-solid interface while maintaining the underlying Cartesian grid in the hydrodynamic domain. The performance and accuracy of the mooring algorithm are compared to the widely-used mooring model MoorDyn, which is coupled to the hydrodynamic solver in REEF3D::CFD. The study demonstrates that the enhanced direction forcing method with the integrated quasi-static mooring algorithm in REEF3D::CFD provides a robust and accurate suite for the numerical analysis of the state-of-the-art FOWT in ocean waves.

Presenting Author: Widar Weizhi Wang Norwegian University of Science and Technology

Presenting Author Biography: Widar Weizhi Wang is a researcher in the development team of the open-source hydrodynamics suite REEF3D at the Norwegian University of Science and Technology where he is dedicated to the research on numerical wave modelling at different scales for a wide variety of topics on ocean engineering, coastal engineering, coastal protection and adaptions and marine renewable energy.

Authors:

Ahmet Soydan Norwegian University of Science and Technology
Widar Weizhi Wang Norwegian University of Science and Technology
Hans Bihs Norwegian University of Science and Technology