The article with the porous cylinders is completely irrelevant to this discussion. In that article the holes are affecting parallel flow which is akin to using screen as a belly pan. We however are talking about perpendicular flow. I found this great article talking about mesh and air flow as it relates to fume hoods.
http://ateam.lbl.gov/hightech/fumeho..._Fume_Hood.pdf
In the article they determine an equation calculating the static pressure created at the face of the screen that is dependent on the air velocity.
P = (V^1.5)/(42.8*10^2.59A)
P = pressure in pascals, V = velocity in feet per minute and A = the free hole area. 1 MPH = 88 FPM.
Using this equation you can calculate the static pressure generated at the face of the screen.
If we take the smallest free hole area at 60 MPH we get over 2000 pascals of static pressure. The question is can this much static pressure block air flow through a screen.
I also found this article about the effect of static pressure on the cfm of a fan
http://www.asi.ksu.edu/DesktopModule...ocumentID=5131
At the end of the article there is a table showing how CFM of a fan decreases with increasing static pressure. In that table the highest static pressure is 0.30 in. water. There are 248.9 pascals in 1 in. water. So 2018 Pascals converts to 8.1 in. water. If you graph the fan CFM vs Static Pressure and extrapolate forward all of the fans listed go to 0 CFM by 0.6 in. water.
And a 25% free hole area screen at 60 MPH generates 8.1 in. water in static pressure. You cannot tell me there will not be some blocking going on with a low enough free hole area screen. I am confident the correct mesh will block most air flow at highway speeds. Some air will likely still be forced through. Is the trade off of not having 100% blocking like a solid piece for a grill block at high speed worth it to gain low speed air flow? If you can have both high speed blocking and low speed flow can you block more of your grill without risking overheating? I think the articles I found and the calculations I have done form a solid theory. Now all that remains is the testing.
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if your formula was to work, then every time we get even a heavy thunderstorm with 50+ mph winds (just about an every day occurrence in the summer), it would pull that screen right off the rails... every single time. (which would be good for me, since then Id have more work than I could keep up with)
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Correct me if I am wrong, from what I could find most residential screens have a free hole area of ~70%. Looking in the table of calculations we see the typical window screen generates 6.83% of the static pressure of a 25% free hole area screen. So the typical household screen is not in the same ball park as one we would consider using for a grill block.