Experimental study of attached splitter plate effects on the wake of a circular cylinder using finite-time Lyapunov exponents

Two-component planar particle image velocimetry (PIV) and surface pressure were used to investigate the effects of an attached splitter plate on the formation and shedding of vortices from a circular cylinder. The instantaneous velocity data is phase averaged using the surface pressure. One of the tools used to visualize and characterize the flow is finite-time Lyapunov exponent (FTLE). This is a Lagrangian technique that identifies local separation. Prior literature shows that the addition of an attached splitter plate alters the classic von K\'{a}rm\'{a}n vortex shedding and that splitter plates longer than a certain length suppress the periodic shedding. A separate study proposes that the shedding of a vortex from a circular cylinder is characterized by a hyperbolic saddle leaving the vicinity of the surface and that the shedding time can be identified in real time using a surface pressure. In this study, the effects of splitter plates on the vortex shedding will be investigated where the plate will range in length from $1.5D$ to $5.5D$, where $D$ is the diameter of the cylinder. The FTLE and wake structure results will be compared with those found in previous studies that investigated the wake of bluff bodies with and without splitter plates.