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DINAME2019
DINAME2019
Vortex Induced Motions of a Moored Monocolumn Platform
Submission Author:
Brunno Pesce , SP
Co-Authors:
Brunno Pesce, Éverton Lins de Oliveira, CELSO Pupo Pesce
Presenter: Brunno Pesce
doi://10.26678/ABCM.DINAME2019.DIN2019-0213
Abstract
This paper deals with the dynamics of an offshore moored monocolumn platform subject to ocean currents. Floating Production Storage Offloading (FPSO) offshore platforms of the monocolumn type are enormous structures designed as oil processing facilities to operate in deep and very deep waters. Usually of circular shape, such structures are moored to the seabed. Being bluff bodies, they are subjected to Vortex Induced Motions (VIM) or simply Flow Induced Motions (FIM) caused by the current flow. In the last decade, a plethora of research studies has been dedicated to this topic, approached either from the numerical or from the experimental side, this latter through small-scale models tested in water channel or ocean basis facilities. The present research work proposes a 5dof reduced order model, in which analytical mechanics guides the derivation of the governing dynamic equations of the platform on the horizontal plane, forced through hydrodynamic forces caused by the wake. The hydrodynamic forcing is dynamically represented with a 2dof phenomenological model, based on the coupling of two van der Pol oscillators, commonly referred to as wake-oscillator models. The reduced order model is applied to a case study, the MonoBR-GoM platform, supposed moored in 500m deep water through chains in catenary configuration. The dynamic response is analyzed and effects on motions due to the nonlinear restoring mooring forces are investigated.
Keywords
monocolumn platform, vortex-induced motion, mooring system, reduced order model, wake-oscillators
