Flow control of an elastically mounted square cylinder by using an attached flexible plate

Abstract

This work numerically investigates the flow control of an elastically mounted square cylinder by using an attached plate placing downstream. The flow control effect by using a long solid/flexible plate for a circular cylinder has been widely discussed. However, the effect of a short plate is not clear. In addition, few knowledge is known for VIV (vortex-induced vibration) suppression effect for a square cylinder by using a solid/flexible plate. The present work systematically studies the influence of plate length and flexibility on VIV suppression for an elastically mounted square cylinder at Reynolds number 150. First, the effect of a solid plate with non-dimensional length varying in a wide range 0.5≤L*≤3.0 is analyzed. Significant VIV suppression can be achieved by using an attached solid plate, even with a plate at a short length. The influence of flexibility is more complex. A short flexible plate is less effective than a solid plate with the same length. On the other hand, a long flexible plate with medium flexibility can further enhance VIV suppression. A maximum 96% reduction in the vibration amplitude can be achieved by using a long flexible plate with optimal flexibility. Additionally, two VIV suppression mechanisms for an elastically mounted square cylinder with an attached plate are concluded, and the influence of flexibility for both short and long plates is also analyzed.