Upwash increases due the increasing pressure beneath, which is caused by restricted flow due to the 'funnel' created by the proximity of the solid ground.
It is a 'channel', and resists the entry of air that would otherwise flow beneath.
The same thing happens in freestream, but the below wing pressure is less there because the escape route is not bound by a second underwing slipstream, the "ground".
It is all about Rate of flow / velocity of wing. And flow restriction, which is ultimately the creator of all lift.
Altering the rate of flow creates the additional lift. But all these 'causes' are concurrent. At altitude, upwash is produced in the same fashion. Ground Effect demonstrates the complete theory, and Bernoulli does not explain lift, as said prior, he explains conservation of energy. Newton describes the mechanics of moving mass around to create a "plane".
Awblain, how can more upwash result in less downwash?
Owain.
The freebie from Ground Effect is the answer to the dilemma. Without increasing AoA, we get more lift at a constant velocity. Why? Because there is an increase of pressure underneath the wing.
The whole idea is to do just that, by deflecting and compressing it.
Last edited by Lyman; 3rd Dec 2012 at 18:07.