Coupled Dynamic Analysis of Vessel/Risers System Including VIV

The present paper describes general methodology and simulation results for risers coupled with a floating vessel. Equations of extensible riser and their finite element formulation are derived and presented in the form, which is suitable to accommodate the effects of contents flow and VIV. Nonlinear riser equations are solved by iterations in global variables. The analysis procedure of coupling between the several risers and the vessel dynamics is described in details. The low frequency coupled vessel motion and riser behavior are numerically simulated. The internal flow effects are investigated in uniform and pulsating cases. It is found that the internal content flow makes the riser stiffer and the riser curvature reduced. In the VIV analysis, the VIV exitation zone of the riser is obtained based on eigen frequencies and the maximum response is evaluated from the corresponding eigen-shapes in the VIV region.