The element that did not move is where the lift went

Surface pressure on a main element and a flap, with the same main element alone drawn behind them. Deflecting the flap has pulled the main element's suction peak from -1.30 to -7.39 — the flap's circulation induces an upwash at the main element's trailing edge, the Kutta condition there responds by increasing that element's own circulation, and the extra lift appears at the front. The flap contributes directly too, but the larger share of the increment is on the surface nobody moved. Nothing in this solve has any viscosity in it.

1 essay calls two-element. The drawing above is what it returns with no arguments at all; every call below passes it something, because a placement that passes nothing draws whichever member of the family the generator happens to default to rather than the one its essay argues about.

It is also the blast radius. Changing two-element changes every figure listed here at once, and on this site it may change what they assert as well as what they show — which is what has to be rebuilt and looked at before the change is believed.