Several people have written to me asking questions about the the airflow
near a wing.
Where does the momentum come from?
Where does the energy come from?
What is a vortex and why should I care?
Why does one dimensional-analysis argument give the wrong answer, while
another dimensional-analysis argument gives the right answer?
In particular, it explains how to reconcile the observed upwash in front of
the wing with the idea that the "ambient" air ahead of the wing has no
upward momentum.
This discussion is the intermediate step in the following sequence:
1. A qualitative discussion at the introductory level (no calculus, and
practically no equations at all) can be found at http://www.monmouth.com/~jsd/how/htm/airfoils.html
2. If you are interested in the physics of what's going on, you can find a
semi-quantitative discussion at the URL given above. This uses some
calculus concepts.
3. If you want the details, at the level of a graduate course in
aerodynamics, there are several decent textbooks available. These use
vectors, calculus of complex variables, and the whole nine yards. An
annotated bibliography can be found at http://www.monmouth.com/~jsd/how/htm/bibl.html