CFD Modelling of Vortex-Induced Vibrations of Slender Marine Structures

During the last several years many experiments have been carried out on deep-water risers that are subject to fluid-structure interactions known as vortex-induced vibrations. Many of VIV aspects are far from being understood and advanced modelling is required to investigate the impact of the phenomenon which significantly affects the service life of marine structures.

The following work is aimed towards the simulation of vortex-induced vibrations of flexible risers using a computational fluid dynamics approach. The present CFD capabilities are able to provide results that adequately agree with the experimental data and can be used to calibrate existing reduced-order analytical models and provide a framework generic for different flow characteristics and boundary conditions. A pressure-based solver is used to model the vortex shedding behind a circular cylinder for a uniform flow as well as to compute lift and drag forces for further motion prediction and investigation of stresses on the structure. When natural frequency of the structure matches the vortex shedding frequency, a phenomenon widely known as “lock-in” can be observed. This results in higher cross-flow oscillations and can inflict a significant amount of damage to the structure.