Fig. 6. Vorticity plot in the case of A₀/c=4.8, =0. Ten frames are shown in the fourth stroke. Red, counterclockwise rotating vortices; blue, clockwise rotating vortices. The wing is in black. (A,C) Computed vorticity; (B,D) digital particle image vorticity data in a 2D slice at 0.65R. See Materials and methods for details. Each pair in A,B and C,D corresponds to the same time during a stroke. The time sequence is indicated by the numbers on each plate. The color scale for vorticity of computation and experiments do not correspond to the exact same contour values, so the figure should be viewed as a qualitative comparison.