Coupled dynamic analysis of a mini TLP: Comparison with measurements

Volume 7: CFD and VIV; Offshore Geotechnics

Zheng

2011

Section: Viv Of Riser With Varying Structural Propertiesmentioning

confidence: 99%

Effects of Varying Tension and Stiffness on Dynamic Characteristics and VIV of Slender Riser

Volume 7: CFD and VIV; Offshore Geotechnics

Zheng

2011

“…Therefore some complicated phenomena, e.g. multi-mode vibration and wider-band random vibration, of the vortex-induced vibration of long flexible risers are frequently observed (Chen et al, 2006;Gu et al, 2012;Heurtier et al, 2001;Lou et al, 2010;Stansberg et al, 2002;Tahara and Kim, 2003). On the other hand, compared to fixed platform in shallow water, floating platform in deep water has more significant motion amplitude, and the coupling between top-end vessel and submarine riser appears to be more remarkable.…”

Section: Introductionmentioning

confidence: 99%

“…Generally, the analysis methods concerning interactions of top-end vessel and marine structures can be classified into two kinds: the quasi-static method (Ormberg et al, 1997;Kim et al, 2001;Spanos et al, 2005;Wichers et al, 2001;Xu et al, 2009) and the coupled method (Bosman and Hooker, 1999;Chen et al, 2006;Gu et al, 2012;Li et al, 2010;Tahara and Kim, 2003). In the quasi-static method, riser is simplified as a spring with lumped mass.…”

Section: Introductionmentioning

confidence: 99%

Impacts of top-end vessel sway on vortex-induced vibration of the submarine riser for a floating platform in deep water

Zheng

et al. 2015

Ocean Engineering

a b s t r a c tThe dynamic coupling between moving top-end vessel and submarine riser becomes more remarkable for floating platform in deep water due to its larger amplitude of top-end motion, compared to fixed platform in shallow water. The impacts of top-end motion on the riser undergoing vortex-induced vibration (VIV) are explored in this study. A coupled hydrodynamic force approach, involving the vortex-induced lift force along with the fluid drag force, is developed, which takes into account the interaction between fluid dynamic force and instantaneous riser motion. Then the dynamic behaviors of the riser suffering both top-end motion and VIV are examined by means of finite element simulations. The effects of the amplitude and frequency of topend vessel sway on riser's VIV are studied. During the riser's dynamic responses, an interesting phenomenon, called nonlinear response amplification, is observed, which demonstrates that top-end motion may be amplified as the motion propagates along riser length. Our numerical results show that the riser's displacement becomes several times larger than that of the case without top-end motion. Moreover, the nonlinear amplification gets more pronounced as the number of mode order drops, but the amplification factor just slightly changes with the increase of sway amplitude.

“…Generally, the methods of those researches can be classified into two kinds: quasi-static method [8][9][10][11] and coupled method [12][13][14][15][16][17][18] . In quasi-static method, riser is modeled by a spring with lumped mass, and only hydrostatic restoring force of riser is considered.…”

Section: Introductionmentioning

confidence: 99%

Effects of Top-End Vessel Heave on Submarine Riser VIV of Deep Water Platform

Volume 1B: Offshore Technology

Guo

et al. 2014

The dynamic coupling between moving top-end vessel and submarine riser becomes more remarkable for a floating platform in deeper water due to the larger top-end motion amplitude, compared with the fixed platform in shallow water. In this study the impacts of top-end heave on the riser undergoing vortex-induced vibration (VIV) are explored in terms of the parametric excitation and the consequent dynamic behaviors. By using finite element simulations based on a coupled hydrodynamic force approach, the dynamic responses of the integrated system including both a floating top-end and the riser experiencing VIV are examined.Our numerical results show that the riser displacement becomes several times larger than the displacement for the case without top-end motion, and the impact of heave on riser VIV response gets larger as the modal order number dropping. Riser VIV amplitude becomes, almost linearly, more profound when the tension ratio, as one of critical parameters that influence the riser dynamic response, gets larger. Moreover, an interesting phenomenon called mode transition is observed, particularly at lower frequency, during modal dynamics response.