Fig. 6. Vortex ring structure and x-velocity around the ribbon fin. (A) Top view, and (B) front end view of isosurface of vorticity magnitude 30 s^–1, colored by the x-velocity normalized by the wave speed V (in this case V=10 cm s^–1). The primary and secondary vortex rings are indicated in A (see Fig. 14A for a schematic of the primary vortex rings). (C) Bottom view, spatial correlation between an isosurface of the same vorticity magnitude as in A (yellow) and an isosurface of x-velocity at 2 cm s^–1 (blue). Primary vortex rings are seen to connect across the fin surface. These results are for t=1.0 s and the baseline case: _max=30 deg., f=2 Hz, /L_fin=0.5, h_fin/L_fin=0.1. Movies 1 and 2 (supplementary material) show the evolution of the streamwise jet from perspective and bottom views, respectively, for the baseline case.