Numerical simulation of a forced and freely-vibrating cylinder at supercritical Reynolds numbers
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Abstract
Recent innovations in the off-shore wind industry have lead to bigger wind turbines and taller support structures. These towers can suffer from vortex-induced vibrations (VIV). The present work couples the open-source CFD solver OpenFOAM with a structural solver to investigate these fluid-structure interactions (FSI) effects in more detail. 2D simulations are performed at supercritical Reynolds numbers and turbulence is modelled trough Unsteady Reynolds-Averaged Navier-Stokes (URANS). Two canonical VIV problems are considered: a transversely forced-vibrating and a transversely freely-vibrating (1 DOF) cylinder. Firstly, the aerodynamic damping was evaluated under different operating conditions by the forced-vibrating model. Furthermore, the effect of the structural mass, stiffness and damping parameters on the VIV response is analysed. Results will be summarised in terms of lock-in maps in the supercritical regime. Lastly, the reliability and accuracy of the CFD-FSI model has been assessed carefully.
Eventually, these CFD results can be used to calibrate the phenomenological models for VIV at full-scale and are therefore a good compromise between engineering use and computational cost. Future work will investigate the effect of the spanwise flow component on the lock-in map, force magnification and wake patterns by means of large-eddy simulations.