Computational study of the three-dimensional wake and performance of a trapezoidal pitching panel

Fish primarily propel themselves forward at moderate to high swimming speeds by undulating their bodies and oscillating their caudal fins which can be found in diverse shapes and aspect ratios. The caudal fin leaves behind a complex hydrodynamic footprint; a three-dimensional wake which exhibits different characteristics at different flow conditions and swimming speeds. In this study, a computational investigation is performed on the wake characteristics and performance of a fish-like caudal fin simplified as a trapezoidal panel undergoing pitch motion in a Strouhal number range of 0.17-0.56 and varying aspect ratio (2-8). Emphasis is placed on validating the flow structures from previous experimental measurements, providing performance data which is lacking in current literature on trapezoidal panels and correlating the wake structures to the performance of the plate at low Reynolds numbers to offer insight in the design of underwater propulsion systems.