Numerical study of galloping oscillation of a two-dimensional circular cylinder attached with fixed fairing device

Galloping oscillation has been observed in the practical applications of the fairing devices on offshore oil and gas risers. The ability of the riser movement prediction codes to predict the galloping oscillation is important since major structure failures due to poor design may be avoided. Few reports have been found on the numerical simulation of the galloping oscillation of the faired cylinders. In the present work, a numerical investigation is performed on the oscillation of a two-dimensional circular cylinder attached with a short fairing device. The cylinder is free to move in the cross-flow direction, supported by a spring and a damper and the fairing device is firmly attached to the cylinder. The flow field is simulated with an unsteady Reynolds-averaged Navier-Stokes (URANS) model corrected with the arbitrary Lagrange Euler (ALE) method and the governing equations are solved with a total variation diminishing (TVD) scheme. The SST turbulence model is used. Under the reduced velocities varying from 3 to 24, the simulation results of the fluid-solid interaction process are obtained and severe galloping oscillations are captured. The mechanism behind the galloping oscillation of the faired device is analyzed combining the cylinder movements and the corresponding vorticity fields.