Time Domain VIV Analysis of a Free Standing Hybrid Riser

A free standing hybrid riser (FSHR) is a proven solution for deepwater floating production systems. In this system, a submerged buoyancy can supports and tensions a vertical riser. The riser top is connected to a floating production system through a flexible jumper. The FSHR has been used in West Africa and Brazil and will be put into application in the Gulf of Mexico. Experimental and analytical efforts are continuing to better understand the vortex-induced vibration (VIV) response of this riser system. This paper presents a comparison of experimental and numerical results of the VIV response of a FSHR. The analysis is performed with a time domain VIV code ABAVIV, which uses the finite element software package ABAQUS to calculate the response from the VIV forcing. Unlike frequency domain VIV codes, ABAVIV captures structural nonlinearities and the transient nature of the VIV phenomenon. Comparisons between numerical and experimental results for buoyancy can VIV response and loading at the bottom of the riser are presented and show generally good agreement. The relative contributions of buoyancy can and riser VIV to the overall system response are investigated. The paper will also include calculated VIV response from frequency domain methods.