Well since I made that assertion, I thought I'd better check, and if you follow each individual streamline, by my reckoning the average deflection down is just over 1/2cm. Only the top three actually go up. I don't think the displacement in a bounded system like a wind tunnel tells you much anyway, and besides, the Newtonian issue is not the displacement but the acceleration imparted to the air.
The article in post 32 does a good job of both explaining exactly how much (a lot !) of air is involved, and presenting a picture which illustrates it.
Last edited by puntosaurus; 21st November 2012 at 18:21.