a question for the aero guys!
 

I.ve been thinking about it for days now. Afther reading a bit into mirror designs and the high preasure at the windshield and high turbulance around the a pillar.

What about spoilers/flaps to fill in the angle between fender and a pillar. A flat plate welded in or if ducktape wil hold for testing or other manners. But i my mind if you box in the high preasure at the base of the windshield and "cut" the air with the same plate for better attached flow on the sides and around the mirrors. Sorry for my schetchy explanation. I.ll try to make a hand drawn schetch and upload it

Here i a quick sketch (sorry for the childish car haha) and the spoiler/flap is filled in. Also i think a car with a bigger transsition from bonnet to windshield would proffit more frome this.

Hope you guys know something about it. Or ill try it when weather gets better and make a coroplast mockup for it and do a a-b-a-b with tufting.

A windshield wiper cover like?

Or like a hood cowl?

Not like that. More like wing end plates on big spoilers. The would trap the high preasure and let it move over the windshield as not to let it spill it around the A pillar. Thus redusing drag around the a pillar.

Ok it would be some trail and error to find the correct shape and size for each car.

I.ve made a simple top and front views to. Also the plates are highlighted.

better make it out of clear Perspex you will have a big blindspot there

Seems like a good idea at first blush, but it would make things worse. The airflow at the base of the A pillar isn't traveling straight back in a way that could be meaningfully 'corraled' like that- it's going across at a good angle. So that plate would cause separation & recirculation behind it, and that would make a mess of the flow along the side of the car.

I think i know what you mean. But would it also be so if it is gap sealed. With no leaks from the high preasure part?

I think if it is sized and curved properly it could work.

Better than a flat plate, sure.

Good luck fine tuning it outside of CFD or a wind tunnel!

It would take alot of trail and error. To make it big enough to not let it spill the high preasure and to make it flow nice

I don't know how hard it would be to make it work. Aerohead turned us on to a way of correcting downstream flow on square-edged forms like trailers and camper shells and even truck cabs and it was a curved "leading edge fin".

It's going to spill regardless. The idea of the curved portion Frank mentioned is to control the spill in a way that keeps the flow "clean" along the sides.

I'm going to play devil's advocate here, but I think automakers have already put a lot of time into optimising A-pillar design for current windshield angles. Short of fully encapsulating & shaping the whole front end from the leading edge of the hood to the roof (which requires adding a second windshield), I don't think there's much to be gained.

And if there's a rear view mirror there it might negate any benefit.

New Civic A-pillar/windshield relationship is kind of similar.

I'm afraid it would be like working with a box plow. no flow over the edges, unless you keep going until it's full. Then you're still spilling over, but you'd be pushing more at the same time.

I have to agree with Frank, the civic has a recessed windshield with a protruding a-pillar and I believe the new Focus and Fiesta have a similar set design. There was a post on here about Mercedes experimenting with a-pillar fences but can't remember it off the top of my head. Also, doesn't the old Beatle benefit from such fences? I'll have to do more digging when I'm not on my phone...

I think the original idea is a neat one just to try and block so much air coming into contact with the side mirror. Let the air up the pillar spill over like normal, but redirect some flow away from the problematic mirrors... Some triangles of coroplast should be easy enough to cut up and stick on for testing. Tuft test the windows and sides of the car and only treat 1 side so you can compare if there is extended turbulence on the non-treated side. I'm assuming the faster you regain attached flow, the better off you are.

http://performancedrive.com.au/wp-co...AB-concept.jpg

The Eolab has fences, but the air can flow through them. They must have done that for a reason.

I first thought it might be for structural reasons then I realized that is probably not the case. Perhaps the fences help bend the air around the A pillar so there's less vorticity.

It might make things worse. If the mirror is visible from the front of the car, it's part of the frontal area. Blocking the flow off the windshield might change the angle of the oncoming air, but that would drive the drag toward similar to the stagnation point.

spacemanspif mentioned old Beetles. This is cribbed from racing 911s:
http://www.gerrelt.nl/mirror/beetle_...alifornia1.jpg
http://www.gerrelt.nl/section-aerodynamics/aerodynamics-vitaloni-mirror.html

Mirrors are problematic because the optical requirement demands a flat plate and they are located in a complex flow. Peep mirrors and fendertop mounted mirrors address this. Peep mirrors are closer to the drivers eye and can be smaller.

The Eolab is interesting. I wonder how much of that is not just styling. Ferrari took the opposite approach...once.
http://i.imgur.com/Z8q8D.jpg

Nothing fancy : the windshield angle is steep so there is less heavy glass but it wouldn't look aero from the side so they made fake A pillars which didn't detract flow (measured).
Aero performance is very much in the back of a car anyway.

high pressure
 

The stagnation bubble atop the cowl area is not responsible for flow over the windshield or A-pillars.It doesn't go anywhere,but rather travels along with the car,stuck right there.When the ventilation damper is open,this pressure pushes air into the HVAC system.
In a rain,you may see the air (pushing water ) go sideways at the bottom of the windshield,at a 45-degree angle at the top sides,and vertical in the center.
As MetroMPG mentioned,if you place a capping plate/fence near the A-pillar base,the transverse flow will trip over it,creating flow separation and turbulence right there.
Modern cars which have the valley between the A-pillars were designed for that.The fenders,hood,windshield,and A-pillars were all done from scratch to accommodate that feature.To dial that in on a car not designed for it might not be doable.If it could,you'd need,according to many new graduate engineers,and also mentioned ,top of the line CFD or a full-scale wind tunnel.
Personally,I'd recommend you spend your time elsewhere.

I had a similar question some time ago :http://ecomodder.com/forum/showthrea...ces-21242.html

By the way, look at the " fences " used around the Shelby Daytonas' windshield.
( The small piece just above the mirrors - you can see them better at 0:46 in the video )
https://www.youtube.com/watch?v=buWIbGEd-lc

Sounds like a popcorn maker too me when at idle.

Already thanks for all your input. I may of may not try it. It was just an idea floating around. And in my mind the ford ka isnt made for aero. So there would be much to win

saw a 2009 merc b class yday and couldn't help but noticing the windscreen looking like its recessed in from the pillars not sitting flush like most cars.
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Now i see these cars. There are alot of cars that have such fences. Peugeot's and citroen's have thos alot. Also some fords and more. but will it be for aero or not. Those would be doable to make and test. Take a 40mm pvc sewage pipe and cut them lengtways and put them on. Make it flush with tape and test it

The nice thing about testing these is you can tuft the area and watch it as you drive (unlike things out back).

2012 Maxima has what you are looking for.

That might work in the rain, but I question whether it would work in snow.

A-pillars
 

Whatever the reason for the 'new' design,it looks like they're a hazard to pedestrians.
Here's a link to a safety concept
http://cms.ukintpress.com/UserFiles/.../42312_1_5.jpg

The 2015 Leaf (and maybe other years?) also have these deep recesses in the 'A' pillars.

Maybe it is just a way to get bigger A-Pillars without creating too much of a blind angle ?
We have those kinds of issues on cars ...

A-pillars
 

Here in the 'States,' roof strength regulations are pushing stronger 'pillars'.
Pedestrian safety regulations are raising cowls.
The submerged cowls may also have to do with safety,and to provide enough pressure for fan-off ventilation.The depression,locked in by the A-pillars may have to do with fresh air as much as drag.
So far,there are no low drag concepts with this submerged cowl.