CFD simulation of vortex-induced and wake-induced vibrations of dual vertical risers
Additional Document Info
Computational fluid dynamics (CFD) simulations of vortex-induced vibrations (VIV) and wake-induced vibrations (WIV) have been performed for two vertical risers in tandem and side-by-side arrangements. Both risers have the same outer diameter of 0.016 m, and the same total length of 1.5 m (L/D = 93.75). However, only the lower 40% of the risers is submerged in water. Two different cases were considered for dual-riser VIV in side-by-side arrangements with center-to-center distances of 2 and 4 diameters. Simulations were also performed for the same two risers in tandem arrangement with different combinations of top-tension, flow velocity, and center-to-center spacing. For completeness, calculations were also performed for an isolated riser to provide a more detailed comparison of the riser motion with available experimental data. In all simulations, the flow field was solved using an unsteady Reynolds-Averaged Navier-Stokes (RANS) numerical method in conjunction with a chimera domain decomposition approach with overset grids. The riser inline and cross-flow motion responses were calculated using a tensioned beam motion equation. The external force terms were obtained by integrating viscous and pressure loads on the riser surface. The computed vortex patterns and dynamic responses of the risers are in good agreement with the experimental data. Copyright 2013 by the International Society of Offshore and Polar Engineers (ISOPE).