FIG. 10.

Geometry E (W/D = 1.3 and α = 1): The evolution of the non-dimensional out-of-plane vorticity and in-plane velocity vectors shows the development of a vortex ring with waveform 2 (PI = 1.43) at An = 1.86 (upper row) and a stationary shear layer with waveform 1 (PI = 0.57) at An = 0.74 (lower row) at various time instants during the cycle. The red dot on the waveform shows the time instant in the cycle. The green lines and the white cross signs depict the vortex structure and its axis, respectively, determined based on Burgers’ model.⁶⁰