Fig. 2. Wake vorticity during fling phase in model Drosophila wings using 2D-DPIV analysis. The images were captured using a commercial 2D-DPIV system and a mini-Nd:YAG laser (TSI, Shoreview, MN, USA). (A) Wing shape and relative distance of five layers from the wing base used for analysis. Scale bar indicates time for the data traces in B–F. (B,C) Fluid vorticity fields at 0.05 stroke cycle after dorsal wing clap in a layer near the wing base (B), 0.33 (C), 0.5 (D), 0.75 wing length (E) and in a layer close to the wing tip (F). Data above each image show circulation in the leading edge vortex (LEV), measured in a region of interest (ROI, white box). LEV circulation when flapping one and two wings are plotted in red and black, respectively. Gray bars in the graphs indicate wing clap and time at which the DPIV analysis was performed, respectively. White lines in panels indicate wing sections. The leading edge of the dorsal wing surface is indicated by a white triangle. The magnitude of vorticity is plotted in color code and arrows correspond to the magnitude of the velocity vector at each point in the fluid, longer arrows signify larger velocities. t=stroke cycle (0–1), R=wing length. See Lehmann et al. (Lehmann et al., 2005) for kinematics and further details on methods.