Force and vortex shedding characteristics of a circular cylinder with flexible splitter plates

In this paper, flow past a circular cylinder with various lengths of flexible splitter plate attachment is experimentally investigated. The dynamic behaviors of flexible plates are closely related to the Reynolds numbers (Re) and plate length. For cases of L/D = 1 and L/D = 1.5, the flexible plates enter deflection mode with the increase of Re. For long flexible plates (L/D > 2.5), a large deformation and periodic flapping mode occurs when the Re exceeds 20000. Subsequently, the pressure fluctuation increases dramatically in central region of leeward surface of the cylinder. The Particle Image Velocimetry (PIV) measurement results show that the vortex formation is much closer to the rear surface of cylinder, which results in the dramatic pressure fluctuation mentioned above. Meanwhile, the mean drag coefficient decreases nonmonotonically with flexible splitter plate length. The Fast Fourier Transform (FFT) spectrum further shows that the vortex shedding frequency is obviously decreased when the flexible plate is long (L/D > 2.0), However, compared with the rigid plate, the vortex shedding from the cylinder is not completely inhibited at L/D = 5.0.