I would absolutely LOVE to be able to have access to a full scale wind tunnel for testing. But on avg you spend a few thousand dollars an hour on a wind tunnel to rent, and that is just not feasible to be honest.
This image I found on line should give you a better visualization of what happens.
And on a automotive application...yes I know its a EVO, but this is a very good visualization of what is going on.
And the fact that air foils work based on air flow differences, the more flow you pass under the lower surface of a wing vs the upper surface on a car the more downforce it generates.
Would love to go into more detail about air foils, fluid dymanics, aerodynamics and so forth. It would get quite nerdy quickly and actually stray away from automotive application and require mathematics and physics background.