I think the solid need not be cambered
You are correct it can be a flat plate but C'mon it's Boeing
Do you think it is physically possible to lift an aircraft by blowing the wing from its own engines?
Do notice I said "physically possible" and not "a practical proposition"!
No it's not possible....a similar proposition to a conveyor belt'
That article discusses boundary layer control i.e an air jet blown though slots add energty to the boundary layer, delaying turbulent flow separation beacause of the increased kinetic energy...but that energy is very expensive and heavy...and exhaustive of fuel
I
t gets murlier and murkier the further that we go in this discussion.
I think
Guppy's explanations should suffice and perhaps a review of Davies
otherwise we are all just beating Tin Lizzie