Flow Illustrator Stand Alone Version (Windows Only)

[Sven7]

No need for more fiddling!



I'm not sure how the undercarriage is in real life but I doubt that lump is there. Anyway, here's what I suggest. When you can, do tuft testing on the rear window to see if you have attached flow. Flow Illustrator says you should but you'll want to know for sure. If you do, leave it stock without any spoiler. If you don't, add the little Kammback thing I threw on there.

In either case you should consider a full belly pan with the rear pointing up just about 5* or so.

Good luck tonight!

[GMPG]

Originally Posted by Sven7

No need for more fiddling!

Good luck tonight!

Can't have one without the other...


Thanks for running that profile for me, unfortunately for me I spent an hour with a cup of coffee and GraphicConverter before I saw your reply. I went back and made a few new profiles, all with a ground referenced to the ground plane in the original line drawing and axle bumps.

1. Otherwise stock.
2. Airdam, no rear wing.
3. Airdam, Cavalier wing.
4. Airdam, Cavalier wing, rear filler.

If you could run those I'd really appreciate it. The various mods and Cav wing are all as close to scale as I can get them.

The stock spoiler really seems to stick up and has a gap under it, which from what I've read seems to be undesirable. The Cav spoiler/wing is attached and looks like it might be better than stock but I'm wondering if no spoiler would be best of all.

Thanks again for running the profiles you already have, I hope it isn't too much trouble to do a few more. What settings are your using btw?

-GMPG

[Sven7]

I'll have them for you in a sec. The car can't be see-through because the program treats that as a bunch of lines, not an object. I'm overlaying them with 40% grey so the program will recognize it. They also need a little more space above the car. I'm doing this as well

Using 120 incoming velocity and 45 viscosity. It's what Chaz recommended. The top one shows the full window.

In my opinion it looks like the axle bumps are really big. They are negating any gains from the rear belly pan on the second simulation. If the thing were attached at the line of that axle and angled up juuust slightly it would help out a lot.

[GMPG]

Originally Posted by Sven7

In my opinion it looks like the axle bumps are really big. They are negating any gains from the rear belly pan on the second simulation. If the thing were attached at the line of that axle and angled up juuust slightly it would help out a lot.

Thanks for the tip on needing to shade the outline, and making the images of course. I'd seen a few people using pictures so I thought maybe the outline would be okay.

You're right about the axle bumps. I'd tried to estimate the height of the engine/transmission across the front of the car but I got it a little low, the actual height is just about exactly where the OE chin air dam is in the top image in your composite and the rear bump really doesn't need to be there at all.

If I'm reading these images right it looks like air dam and no spoiler (Bottom image) is slightly better than the stock setup and air dam and Cavalier spoiler (3rd from top) is the best of the three non-stock options?

Not shown here is the trailer hitch installed on the car. I use it too often and it's too much of a PITA for me to remove even though it's dead weight the rest of the time. It doesn't hang down below the bodywork though and it would make a good mounting point for pan of some sort at the rear that I could tuck up onto the lower lip of the rear bumper cover.

[Ecky]

Where can I get a copy of the program? Link in the first post doesn't work anymore.

[niky]

+1.

[GMPG]

Here is the link to the Beta version of the software. From what it says on the page I believe this will be the home of future versions too. Windows PC only at this time but Mac and *nix versions are probably coming in the future.

https://www.imperial.ac.uk/aeronauti...llustrator.htm

[niky]

Thanks!

[ecoxantia]

What reynolds number are people aiming at with their FI settings? I read that a real car would be 10^5 or so; however FI doesn't like it that high. Then again we are talking pretty pictures not real life...

[ChazInMT]

Originally Posted by ecoxantia

What reynolds number are people aiming at with their FI settings? I read that a real car would be 10^5 or so; however FI doesn't like it that high. Then again we are talking pretty pictures not real life...

Yes, if you know what the air flow around your car is supposed to look like, then this will illustrate what you have in your head by tweaking the Velocity & Viscosity. The real world Reynolds numbers are Totally Non-Applicable in this program, they always have been. Even in the old online version it was N/A, but people ignored that part of the programmers notes about it.

Keep in mind that these are 2D illustrations as well, cars live in a 3D world.

So, this will let you make a movie of what you think flow will look like and, if you have a little idea about what it might be, you can make changes and see what they might look like. Not perfect by any means, but it's free, simple, and gets people thinking about aerodynamics while having some fun.

Bottom line, This is not a wind tunnel simulator. It makes pretty pictures. But there is some truth to using it as a design analysis tool, it would be like measuring the length of your car by driving it onto a football field and using the yard markers, you will not know precisely how many inches long it is.