Okay, used dissolve blending on the red portion above, then measured the red

(yes, the original image I've been working with has been 800x800 the whole time, I've resized to 500x500 for bandwidth/viewing sake...but resizing with a dissolve does not work so well )

52.8% of the red is in the center half, so airflow is basically even (this is without a shroud, just the small spacing already provided). Also note the corners probably don't actually have 0 airflow.



(And of course note this is not an exact science, at all, but just a series of approximations, but considering how near-50% they're landing, it's saying something, IMO)