Originally Posted by
Vessbot
They don't teach this anymore, it's been corrected. But there are still stragglers, since it's so simple and elegant and ties everything together...
The starting and stopping vortices are opposite to each other. The starting is CCW, stopping CW (stopping same as bound vortex). So all 4 vortices surrounding the rectangle swept by the wing's motion (starting, stopping, and 2 wingtip vortices), curl so the top goes inward, and the inside goes downward, which matches the downwash where the lift occurred.
https://www.youtube.com/watch?v=VcggiVSf5F8
https://www.youtube.com/watch?v=bvV7-9wAXc0
My bad, late nite. A CW rotation around a section has a CCW start vortex, and the stop vortex is
CW, same. as if the section is removed from the fluid, the flow continues CW.
.