This link was posted recently to a racing discussion

http://www.wb-sails.fi/news/470StreamAnim/index.htm#

Not sure how useful this is, but the pictures are cool. One of the
things I found interesting was the vertical difference in air flow,
and the difference in pressure distribution between the main & jib. On
the jib, the max pressure differential is much further forward.

Also if you look at the photos of the sail, they are much flatter than
often said to be ideal (there is no reference to wind speed, it might
be light air) and the drafts are aft. Also it shows a vortex off the
head of the jib.... now the question is, does a frac rig benefit
because the mainsail supresses the jib's tip vortex, or does the jib
vortex hurt the drive of the mainsail?

This is kind of theoretical, I wich I could actually go sailing but
right now everything is covered in snow & ice. Maybe later this
week.....

Fresh Breezes- Doug King