VORTEX SHEDDING CHARACTERISTICS OF A FLOW-INDUCED VIBRATING CYLINDER: EFFECT OF RIGID VERSUS FLEXIBLE SPLITTER PLATE

The present work is based on control of frequency and patterns of vortex-shedding for an elastically mounted cylinder with a detached rigid/flexible splitter plate. The flow control technique is studied using an immersed interface method-based in-house code, for a smaller and larger gap G* (0.3 and 2.0) between the two structures and for various reduced velocity U* (2−12.5). The nondimensional study is presented for constant structural properties of the cylinder and the flexible plate at Reynolds number Re = 100. At the larger gap G* = 2.0, the trend of shedding-frequency variation with a splitter plate is similar to an isolated vibrating cylinder. However, both rigid and flexible plates lead to a small suppression in the frequency at smaller and larger U* , and the flexible plate leads to a marginal enhancement at intermediate U*. At smaller gap G* = 0.3, frequency suppression due to the splitter plate increases, with increasing U* , with a larger suppression for the rigid plate. At G* = 2.0, vortex-shedding patterns also resemble an isolated vibrating cylinder, except a novel C(2P') pattern at intermediate U* for a rigid plate, whereas at G* = 0.3, the vortex-shedding pattern shows various transitions−2S to C(2P'), C(2P') to 2P', and finally 2P' to a complex nonperiodic shedding pattern with increasing U*. These transitions correspond to a decreasing shedding frequency, presented in a vortex-shedding pattern map overlapped with the frequency response. The mechanism for the novel C(2P') and 2P' patterns is discussed. The splitter plate significantly modifies the frequency and shedding patterns of a circular cylinder that can be utilized for several engineering applications.