Creates a very pronounced outwash similar to the cascades used previously.
The pressure side of the wing creates an outwash as its less loaded on the outboard side compared to the inboard side resulting in a favourable pressure gradient in favour of the outboard side (not as much as one might expect due to the pressure impingment between the outboard side of the wing and frontal stagnation/high pressure region of the wheel). The suction side of the wing creates an inwash again due to a favourable pressure gradient this time in favour of the inboard side due to the presence of a lower pressure in that region compared to that of the outboard side.
The Image says it all...