Investigation on vortex-induced vibration of twin rectangular 5:1 cylinders through wind tunnel tests and POD analysis

Abstract

This paper investigates the vortex-induced vibration (VIV) performance of twin rectangular cylinders with an aspect ratio of 5. A series of wind tunnel dynamic tests and pressure measurements were carried out. Proper orthogonal decomposition (POD) technique was applied to the fluctuating wind pressure field around the cylinders at wind velocities corresponding to the maximum VIV amplitudes. The experimental results show the downstream cylinder has larger VIV responses than the upstream one for most cases. The gap distance has a critical impact on the aerodynamic behavior of twin rectangular cylinders in terms of VIV responses, mean and fluctuating pressure distribution and aerostatic coefficients. POD analysis indicates the first mode is dominant to the VIVs of the downstream cylinder, while the second mode is closely related to the VIVs of the upstream one. The fluctuating lift and moment coefficient time-histories reconstructed with the first two modes agree well with the results from the original data.