Hydrodynamic loading and response of offshore risers

摘要

A prediction model for the response of offshore risers which couples the dynamic solutions regarding the two planes of vibration of the structure is proposed. This model accounts for the hydroelastic interactions which take place between the structure and the fluid when the riser oscillates under a shear/oscillatory flow. A conventional approach for the fluid/structure interaction throughout the riser is adopted by considering a finite-element structural model and a hydrodynamic loading model. The hydrodynamic model considers the attenuation experienced by modal waves when they travel along the riser and the way it addresses the multi-mode problem represents a novelty in this research field. The results based on this methodllogy for an offshore riser under realistic flow conditions seem to be very promising. Sensitivity analyses on some flow parameters confirmed the consistency of the reults in physical and mathematical terms. In addition, the way the vortex-induced forces and the fluid damping in the transverse direction are addressed also represents a novelty.