I also think that louvers are used rather than just openings in attempt to create a venturi effect. Seeing as how most louver designs actually bulge up just before the vent, then the dip down for the opening... creating a little high pressure area that transitions quickly to a low pressure air with an opening... well that's the formula for a venturi. If successful, these louvered vents at speed should be pulling air out quite well.
How technical it gets after that is probably the type of stuff that would hurt the brain. My personal belief is that further spaced gradual louvers like the Siebon TS will have a more effective venturi effect, and that steeper more rapid louvers will have superior airflow volume with less venturi effect. I have really good reasons for thinking that, but I dont want to say it aloud and then have someone who is way smarter come in here and make me look like an idiot
