Comparative Study of the Flow-Induced Vibration of a Circular Cylinder Attached With Front and/or Rear Splitter Plates at a Low Reynolds Number of 120

Abstract

This paper numerically investigates the flow-induced vibration of a circular cylinder attached with front and/or rear splitter plates at Re = 120. The effects of plate length and plate location on the hydrodynamic coefficient, vibration response, and flow wake are examined. The results reveal that the hydrodynamic coefficient of the cylinder with a single rear plate is significantly reduced at Ur = 8 (Ur is the reduced velocity), resulting in the VIV suppression. However, the galloping is excited at Ur > 8 due to the hydrodynamic instability, accompanying with the rapid jump of response amplitude and hydrodynamic force as well as the abrupt drop of response frequency. The alternate reattachment of shear layers on the plate surface introduces an extra lift force that strengthens the vibration response. By introducing an individual front plate, the separation point of cylinder-plate body moves downstream, leading to the delayed vortex shedding and narrowed wake flow and hence the VIV suppression. The vibration exhibits variable patterns when the cylinder is equipped with bilateral plates, including the typical VIV mode, weak VIV-galloping coupling response mode, and IB-galloping-DB mode (IB and DB represent the initial branch and desynchronization branch, respectively). The galloping branch in IB-galloping-DB mode is observed with an abrupt drop of response frequency as well as a tiny time lag between displacement and lift force. The vibration response is significantly suppressed by the cylinder with 1D front plate and 1–2D rear plate due to the more streamlined profile.