Thank goodness I put in the disclaimer. I knew I was going to come up short sooner or later. You are quite correct. The velocity does increase over the top of the wing since the air flowing over it has to travel a further distance (for most airfoils or a symmetric airfoil at some positive angle of attack) than the more direct route under the wing.
Thanks for the correction, Ben.
-Q.
Originally posted by Ben Lanterman
a088008 you said ------ So, the major effect is to reduce the velocity of the air flowing above your hand. -------
No, most anything that is airfoil shaped including your hand in the wind has an increase in velocity over the curved parts or if it is a flat plate when it is at an angle of attack. Along with the increased velocity of the air flow is a decrease in pressure. Now in the case of a airfoil or flat plate at some angle of attack the velocity over the upper surface is much higher than freestream and is higher than the velocity under the wing. This gives the pressure gradients shown in the figures of Section 3 and that makes lift. Look at the pictures at the bottom of Section 3.