Flow-induced vibrations of a serrated flexible splitter plate

We experimentally investigate flow-induced vibrations (FIV) of a cantilevered flexible splitter plate with triangular trailing-edge serrations mounted downstream of a circular cylinder. Seven plate configurations, including two non-serrated baseline plates and five serrated plates with varying serration heights, were investigated in a low-speed wind tunnel over a Reynolds number range (based on diameter) of 4×103–5×104. Structural response and wake characteristics were measured via laser displacement sensing, high-speed imaging, and hot-wire anemometry. All plates exhibit three regimes with increasing free-stream velocity: initial excitation, transition, and synchronized response regime inferred from frequency matching. The synchronized response regime is characterized by frequency matching between the plate oscillation and the wake frequency near the second natural frequency of the plate, accompanied by large-amplitude limit-cycle oscillations. Trailing-edge serrations shift the onset of the synchronized response regime to higher reduced velocity and alter the amplitude and frequency response relative to the base plate 1. Increasing serration height modifies the effective length and structural properties of the plate, which together increase the dimensionless root-mean-square displacement by 25.9% and reduce the dimensionless frequency by 14.9% in the synchronized response regime for plate 5 relative to base plate 1 at a reduced velocity of Ur=7.71. Flow visualization shows that serrations generate localized vortex formation at the serration gaps, suggesting enhanced wake instability and stronger fluid–structure interaction. These results establish trailing-edge serrations as a passive control parameter for tuning FIV, relevant to energy harvesting, aeroelastic control, and vibration mitigation.