You got that backwards, top is curved/bottom is flat but yeah that's right. The curve creates a greater distance, making the air flow faster according to Mr. Bernoulli. I had to study this stuff years ago, but my logbook vanished a few hours from my solo.

I was confused for a sec, but now it all makes sense how vortex generators on the roof would effectively kill the Bernoulli effect by slowing/disturbing the air flow (all things being equal and assuming constant flow under the car).

 

ok, having read a bit more (so i can quit talking out of my butt), the curved surface of the wing causes the attached airflow to speed up, which results in a lower pressure area. if that's the case then, anything on the roof of the car which adds turbulence should slow down the air, raising the pressure (although with a drag penalty).

 

http://travel.howstuffworks.com/airplane8.htm

 

Exactly what I was saying. Make the assumption that a car is shaped like an airplane wing (which it is, just not a good one). If you make turbulance on the top, you lower the speed and therefore increase the pressure of air above the car.
I'm still almost certain the Evo's spikes help becuase of this increase in pressure and not because of any effect it might throw at the rear wing. The nature of the way down force is meassured, however, makes the spikes look like they make the wing better...but really, they just help raise the air pressure above the car so it has more downforce over all. I think. The spikes definatly add drag though, that's a no brainer.

 

yay i've learned something today.

 

its all black magic and devils speak

 

go back to editing your ACL's and leave this to the real engineers.

 

It looks like the fins direct more fast moving air down the rear window, so that would actually lower the pressure on the rear of the car.

If you look at a race car usually the rear spoiler is slightly lower than the roofline, so it is in the fast stream of air coming off of the roof of the car. The evo's spoiler isn't tall enough to accomplish this by itself, so the vortex generators aid in altering the flow of air down closer to where the spoiler is.

 

acl's are for CCNA's foo

im mui l33tAr then that..

in fact i am toying around with meterpreter and passiveX right now.. pretty damn cool stuff...

esp passiveX.. mui ninjah

 

I'm not convinced the fins make the air move faster down the window. It seems to me that laminar air flow (big sheet of air not hitting the fins) would be faster and lower pressure than air that has fins stuck into it due to the increase in turbulance, but the article by motortrend seems to say what you're saying.

 

if we look at the flow diagrams in the article, the car tested has no spoiler, so we can't really see the difference in flow to the spoiler itself.

 

I'm pretty sure the spoiler is shown...

I think the blue and green areas are slower high pressure areas and the yellow area is low pressure.

 

I think you're right on the labeling. I don't really trust those pictures, though, because the red areas in front of where the vortex generators are don't look similar enough...I'm thinking maybe some photoshop data manipulation...

 

oh yeah, i bet that is the spoiler

it was so itty bitty i dinna even see it.