Effects of upstream body on pitching trapezoidal panel

To understand the effects of an upstream body on the wake characteristics of an oscillating propulsor, volumetric reconstructions of phase-averaged velocity field measurements were collected and analyzed. Two experiments were conducted and their results were compared using using qualitative wake characterization. Both datasets had a pitching frequency of 1 Hz, a maximum pitching angle of ±15^◦, and a resulting Strouhal number of 0.37. The Strouhal number was selected for comparison with existing data from a similar experiment. In the previous experiment, an isolated, rigid, trapezoidal panel was pitched about its leading edge. The current work uses the same panel and motion as the first with the addition of an upstream, stationary idealized fish-like body. Together these datasets suggest that a stationary, upstream body does not significantly affect the large-scale wake deformation phenomena, including transverse expansion and spanwise compression. The addition of the upstream body did affect the presence of small-scale structures that are present in the isolated panel case but not in the upstream body case. It is also shown that the upstream body potentially reduces the net thrust produced by the system.