"Given that my last link to a video was not as fascinating to others as I
found it (I thought the injection of dye into the water to see the vortex
ring was pretty special)"
Personally, I did find the entire video fascinating, as well as informative,
and thank him for submitting it.
Don
Dr. Donald G. Polvani
Adjunct Faculty, Physics (Retired)
Anne Arundel Community College
Arnold, MD 21012