Side window tufts pointing up?
 

After tuft testing my wipers on a 1991 Civic Wagon, I thought I'd move the tufts to the side windows and compare both sides. I only have a driver's side mirror. No surprise that there's a bunch of turbulence behind the mirror, but I'm wondering what's happening here on the passenger's side.

http://img.photobucket.com/albums/09...tuftsright.jpg

Why are the front tufts pointing up? Both sides have it, but it's much clearer on the mirrorless side.

My VX does the same thing watching water droplets move on my mirror-less passenger side.

Looks like a very small vortex is generated by the trailing edge of the A pillar. But it look s like the flow re-attaches quickly enough.

My Insight does the same, with water flowing up the glass on the side where the mirror used to be.

Air is flowing up and over the car in the windshield area. As it wraps around the A-pillar, it still has momentum. I don't see vorticies.

i have observed the same thing on my car.

i found a cfd picure that shows what goes on, because of the similar observations i think this happens on most vehicles of this layout.

http://i77.photobucket.com/albums/j5...6c4264_075.jpg

i suppose this is why the shape of the A pillar is more important than one would guess at first glance.

it seems a somewhat complex effect, and i can't really juge if it's good or bad or where the air should go ideally ( i suppose over the car). but it's interesting to note the airflow seems to originate over the side of the hood, and after it's trip over the sidewindow seems to return to the roof.

perhaps another reason why roof racks might hurt FE!

I noticed that having the driver's side front window open causes that side of my kammback to shake. That CFD model shows why. It's not allowing the air to roll onto the roof and over it.

Having the rear windows open doesn't seem to have any effect. Unfortunately, only the passenger side one works. I'll probably check the wiring on it later and make sure it's connected properly. If not, a new motor might be in order, since I removed the AC and summer is coming.


If you tuft test it again, try it with the window down a crack.

low pressure
 

The air going around the A-pillars and over the roof is traveling much faster than the ground speed of the car.
To satisfy Daniel Bournouli's ( sp?) Theorem,the pressure must be lower there.
The tufts are attempting to 'reach' the lower pressure regime and achieve equilibrium.
This is why you don't drive with a hatchback open,as the exhaust fumes also want to migrate through the cabin when the front windows are cracked.

I don't recall a vehicle that DIDN'T do that. Good for smokers. Good for releasing other types of cabin fumes as well. :)

Cheers
KB

I will have to tuft test my zigzag tape on the 'A' pillar -- I think it helps reduce this vortex.

http://img.photobucket.com/albums/v7...d/DSC_1375.jpg

Thanks everybody! Tuft testing is fun, I might do the whole car! :D

I'm not sure if those are large enough to have any effect. Definitely tuft test it.

I found my yarn and masking tape, so I'll be doing a bit of testing myself soon.