A three-dimensional simulation of Vortex Induced Vibrations (VIV) on marine risers at high Reynolds number using computational fluid dynamics.

摘要

The flow of seawater around marine risers is subject to vortex shedding which excites oscillations known as Vortex Induced Vibrations (VIV). When the VIV frequency approaches one of the natural frequencies of the structure, resonance occurs. This results in enhancement of the vibration amplitude of the structure and may have potentially destructive consequences. At present, the prediction of this phenomenon is one of the most challenging areas in the offshore industry.; The focus of this research is on the development of a new approach for simulating vortex induced vibrations on marine risers at high Reynolds numbers using a Large Eddy Simulation (LES) computational fluid dynamics code. This method considers the span-wise variation of the lift and drag forces, and determines the moment acting on the cylinder. The predicted motion then consists of a rotational component to accompany the traditional cross-stream translation.; A simulation of flow around a stationary cylinder was performed to establish the vortex shedding pattern and determine the lift and drag coefficients. At this point a harmonic model was invoked and the cylinder was free to respond to it's shed vortices. Results are presented for the simulation of turbulent flows past a 3 m long cylinder with 1 m diameter, undergoing vortex induced vibrations at a Reynolds number equal to 1 x 105.