Lower vorticity tail changing in amplitude from -10 to 10 as upper tail is fixed at 10

 

Animation of periodic vortices in a stagnation point flow showing how the form of the vortices varies as the vortex tail coming from below changes from being equal and opposite to the supply from above to being of the same sign. The left image shows the flow when viewed along the axis parallel to the direction of the diverging flow in the background stagnation point flow. The middle image shows the perturbation vorticity, and the right image shows the perturbation stream function. In this sequence the strength of the background stagnation point flow is fixed.