Coupled NS/SPH Analysis of Off-Shore Wind Turbine

Abstract

This paper presents results of numerical computations for floating off-shore wind turbines (FOWTs) using, as an example, a machine of 10-MW rated power. The aerodynamic loads on the rotor are computed by the Helicopter Multi-Block (HMB2) flow solver developed at University of Liverpool. HMB2 solves the Navier-Stokes equations in integral form using the arbitrary Lagrangian-Eulerian formulation for time-dependent domains with moving boundaries. Hydrodynamic loads on the support platform are computed using the Smoothed Particle Hydrodynamics (SPH) method, which is mesh-free and represents the water and floating structures by a set of discrete elements, referred to as particles. The motion of the FOWT is predicted using a multi-body dynamic model (MBDM) of rigid bodies and frictionless joints. Mooring cables are modelled as a set of springs and dampers. All solvers were validated separately before coupling, and the results are presented in this work. The importance of coupling is assessed and information about coupling algorithms is presented. The loosely coupled algorithm used in present work is described in details alongside the obtained results.