Wake characteristics of a bio-inspired propulsor behind a streamlined body

A stationary streamlined tuna-like body was added upstream of a pitching trapezoidal panel to investigate how the wake of a whole fish model may differ from an isolated caudal fin model. Stereo particle image velocimetry was conducted in multiple planes along the lower half span of the panel, both with and without the upstream body. The data was phase-averaged, mirrored about the midspan plane, and interpolated into a volume. The Strouhal number was 0.37 and the Reynolds number was 17000 (with body) and 2300 (panel only). In both cases, the wake deformation exhibited transverse expansion and spanwise compression. Spanwise vortex cores lost coherence at the midspan at similar streamwise locations in both cases. For these reasons, the effects of a body’s boundary layer did not alter the main structure of the wake; however, several small-scale structures only appeared in the wake without the model body. Future experiments will involve actuation of the posterior half of the body in addition to the model caudal fin.