Numerical simulations of circular cylinders outfitted with vortex-induced vibrations suppressors
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We present numerical simulation results for two-dimensional incompressible flow past a circular cylinder outfitted with a fairing. Of interest is the response to vortex induced vibrations (VIV) for low mass ratio and damping and high Reynolds numbers. The cylinder and fairing configuration is allowed to undergo three degree-of-freedom motion; where in addition to XY motion, angular motion is allowed. We consider the case of zero torsional damping and find that VIV suppression is sensitive to the value of the torsional stiffness coefficient. The rotational spring-back of the fairing is key in effectively suppressing VIV. For a transitional Reynolds number of Re=105, we make use of a Smagorinsky Large Eddy Simulation (LES) model to account for sub-grid scale turbulence effects. At a Reynolds number of Re=106, we make use of the Reynolds-Averaged NavierStokes (RANS) equations and a two-layer k-epsilon turbulence model to account for turbulence effects. Overset (Chimera) grid capabilities allow for grid components attached to the structure to move and rotate freely in fixed background meshes, avoiding the overhead cost of grid regeneration as the structure moves on the fluid mesh. Copyright 2006 by The International Society of Offshore and Polar Engineers.