Effects of trailing edge shape on experimental propulsive performance and wake structure of biospired pitching panels

Prior experimental research on bioinspired propulsion has often modeled a caudal fin as a trapezoidal panel to investigate propulsive performance. Performance is often directly measured using fixed-velocity or self-propelled swimming experiments, and is correlated with observations of the wake structure based on flow field measurements. The current work analyzes experimental data for five different panel planforms of varying trailing edge shape (forked to pointed geometries) that represent a range of propulsive appendages of aquatic animals. Phase-averaged particle image velocimetry (PIV) is used to capture velocity fields that are interrogated using finite-time Lyapunov exponents (FTLE). Maximizing features of FTLE scalar fields, such as ridges and saddle-like intersections have been shown to correlate with important dynamic phenomena such as vortex shedding, flow separation, and peaks in propulsive performance. While previous work has highlighted certain geometries that produce higher thrust or efficiency, this work will explore the associated changes in the wake structure uncovered by the FTLE analysis.