Internal flow effect on the cross-flow vortex-induced vibration of marine risers with different support methods.

The present work investigates the effect of internal flow on the vortex-induced vibration (VIV) characteristics of a marine riser under different boundary conditions. A numerical model of the riser structure is established by considering the complex flow fields. The developed model is solved by the finite element theory and Newmark method, and it is verified by the experimental data. The effects of internal flow velocity and density on the vortex-induced dynamic responses with different support methods are studied. The results demonstrate that among different support methods, internal flow effect (IFE) has the greatest influence on the vortex-induced response of the riser with hinged-cantilevered support. In the case of hinged-cantilevered support method, the increment of the internal flow velocity and internal flow density has a negative influence on the vortex-induced vibration of the riser. In the case of fixed at both ends support method, the vibration amplitude and mode of riser decrease with the increment of flow density in riser. For the hinged-hinged support condition, the increment of the internal flow velocity slightly increases the amplitude of the riser and the vibration amplitude of riser decreases with the increase of density. This research may provide an efficient method for the VIV prediction, optimization design and operation control of the marine risers in practical applications. [ABSTRACT FROM AUTHOR]