Dynamic behavior of pipelines and risers due to vortex-induced vibration in time domain

Vortex-Induced Vibration (VIV) plays an important role in the design of oil and gas production systems in offshore pre-salt fields in Santos Basin, Brazil. The importance is represented by the large depth of petroleum reservoirs bellow the subsalt layer, the ultra-deep waterdepth and the far distance of the oilfield from the coast. Very aggressive fluid components like CO2 and SO2 present in the produced petroleum make more complex the necessities in terms of material properties for pipelines and risers, which will increase problems due to the fatigue. The VIV in offshore structures is complex and still not been completely understood, particularly for current with high Reynolds number (Re). This paper describes a time domain simulation of the dynamics of pipeline and risers subjected to VIV. A semi-empirical model is adopted to calculate the cross-flow force due to VIV based on the lift coefficient and Strouhal number. This force is evaluated by a Morison-type formulation. The flow is assumed two-dimensional and the shedding frequency is not locked on to the structure vibrating frequency. The proposed simulation model is validated through comparisons of its results with experimental data. © 2011, Sociedade Brasileira de Engenharia Naval.