Edit: I know that the suction holes reduce the boundary layer; I am wondering if there is a reason why they are placed far ahead of the engine’s intake. My thinking is that the long duct past the holes will form its’ own boundary layer, hence reducing the effectiveness of the holes.
Looking at the picture of the Eurofighter inlet, the suction holes for the boundary layer are located far forward from where the engine actually starts.
Why are the suction holes not located closer to the engine?
Surely, the long duct aft of the suction holes will develop its' own boundary layer - which is what the suction holes were reducing in the first place?