Numerical investigation on vortex-induced vibration of twin tandem circular cylinders under low Reynolds number

Abstract

Based on the FEM solution of incompressible viscous Navier-Stokes equations in the frame of arbitrary Lagrangian-Eulerian (ALE), a two-dimensional numerical model was developed to investigate the vortex-induced vibration of twin tandem circular cylinders under low Reynolds number. With the numerical simulations, the upstream cylinder was fixed, while the rear cylinder was allowed to freely oscillate in both transverse and stream-wise directions. The damping ratio 0.007 and the reduced velocity varying from 3.0 to 12.0 were used for the computations. The effects of the in-line center-to-center distance (LX/D=3.0, 5.0, 8.0) and the mass ratio (m*=5.0, 10.0, 20.0) on the displacement of and forces on the downstream cylinder were examined. The numerical simulations indicated that the spacing ratio (LX/D) has a great influence on the VIV responses in terms of lock-in band, displacement and fluid forces. Several flow modes under different spacing ratios and reduced velocities were observed, they were closely related to the VIV responses. It was also found that the change of the mass ratio may give rise to different characteristics of VIV responses for twin cylinders in tandem arrangement under low Reynolds number.