2008 CDG Concept - CFD Analysis

miqi23 · Post 20 Jun 2006, 02:57

Couldnt find any thread on this, actually I did not bother looking for it

Anyways I should upload more images on this. Here is a starter.

[IMG:1209:711]http://img132.imageshack.us/img132/6355 ... cal4rz.jpg[/img]

Thanks

miqi23 · Post 20 Jun 2006, 12:51

Here is another one, 4 vortices, twice the amount of vortex drag in 2008 compared to now.

[IMG:1209:711]http://img136.imageshack.us/img136/3369 ... al25jk.jpg[/img]

kilcoo316 · Post 20 Jun 2006, 13:01

Have you modelled the diffuser?

Could you give details on the upwash in the wake of the car, from the ground to wheel height?

ackzsel · Post 20 Jun 2006, 13:48

I don't see any influence from the tires to the airflow. Is that because that influence is very insignificant or wheren't the tires rolling in your simulation?

miqi23 · Post 20 Jun 2006, 15:10

Actually I have not modelled the diffuser correctly since my aim was to study the effects of wheel spin on wing performance.

The current wake structure you are seeing is slightly more than half a car length behind the car. If you add the diffuser then add a little bit of more wake but I can tell you that it is still much better than what we have now i.e. 2006 season.

I shall upload few more screen shots showing the comparison between 2006 and 2008

Thanks

P.S. Yes the tire is modelled as spinning! The streamlines you are seeing in the second image are way above the tire hence you are not seeing any sort of effect.

kilcoo316 · Post 20 Jun 2006, 15:41

Sorry for appearing so inquisitive, but what software did you use? Fluent/Star/CFX?

What format is the CAD geometry in? [I'd love a copy if I could use it

]

I'm wondering how significant the effects of the diffuser will be - in my own opinion, the majority of the current problem stems from the diffuser, not the rear wing [I think its too high above the ground to cause upwash effects to the degree suffered in F1 - for the same reason I'm quite skeptical of the benefits the CDG rear wing is supposed to bring]. But maybe I can sneak a job onto the supercomputer at work when no-one is looking to see what it does

Post 20 Jun 2006, 16:03

you should stick a car behind it then go take a nap for a few hours while it converges

in about a month they should have the super computer up and running here and i could do some areo runs

dumrick · Post 20 Jun 2006, 16:52

Back to my personal question for some months though: you are moddeling the new wings with a similar carbody to the one currently used to maximize the central rear wing efficiency... what tells you (and FIA...) that the bodyshape won't be changed?

If I had no central rear wing to worry about its efficiency, I would try a wedge-shaped upper carbody or some other resource to get some downforce from that area. That can make a lot dirtier trail than the one you and the FIA are estimating...

Just look at current shapes now: flip-ups and winglets in the edges of the body, where they don't affect the airstream for the rear wing. With CGD wings, these air-dirtying devices (as possible by regulations) will move to the centre of the body and could make the whole decision of implementing the CGD wings look ridiculous.

miqi23 · Post 20 Jun 2006, 17:33

The change from 2007 to 2008 is quite significant. You should appreciate that a lot of changes has been made to the current regulations, however to successfully blend your self in the 2008 season it is best to analyse what can be used from the current regulations to minimise the time required to design a new car.

The car you are seeing in the images are actually a modified 2006 car to meet the 2008 regulations. As I said minimum changes and still meet the 2008 regulations! However, the new rules has opened a new door for further research in aerodynamics. The following image is an analysis on the actual car with the diffuser producing the up-wash which is causing a lot of problem nowadays. I did that to study the performance of newly designed rear wing with close proximity to the car.

[IMG:1209:711]http://img97.imageshack.us/img97/4793/2 ... al18ck.jpg[/img]

Kilcoo, the flow solver used for these analysis was Star-CD.

The following shows the streamlines on the 2008 car, its pretty much apparent that it will be effective. As far as the flip-ups is concerned to cause dirty air etc, read the rule book 'dumrick', any object causing the airflow to disturb at the rear of the car would not be permitted

Simple as that. What ever you do, if they find it working you will be asked to remove it!

[IMG:1209:711]http://img61.imageshack.us/img61/9253/2 ... al21dm.jpg[/img]

As I said before, the aim of this study was to study the effect of wheel spin on wing performance since no work has been done on it before.

Thanks.

miqi23 · Post 20 Jun 2006, 18:38

flynfrog wrote:you should stick a car behind it then go take a nap for a few hours while it converges

in about a month they should have the super computer up and running here and i could do some areo runs

Yes, if you have access to a super computer and can run a job on it then I can send you a CFD file with two cars in a row. Its quite hard for me to sneak in a CFD job on our cray on something we are not working anymore for a while.

Which flow solver would your cluster be using? So that I can generate the mesh in that format.

Many Thanks.

Post 20 Jun 2006, 19:27

i can run it on star cd but i prefer star ccm

we have fluent as well but ive never used it

http://blogs.zdnet.com/emergingtech/index.php?p=235

this will be the computer

and yes you can veiw your results in full immersive 3d

Jersey Tom · Post 20 Jun 2006, 22:56

..sneak in a job on your Cray? Jeez. Where do ya work?

zac510 · Post 20 Jun 2006, 23:23

Great visualisations miqi! Thanks.

I would have thought the upwash from the car would be much greater but I realise the upwash from the rear wing elements is not shown.

miqi23 · Post 21 Jun 2006, 13:25

flynfrog wrote:i can run it on star cd but i prefer star ccm

we have fluent as well but ive never used it

http://blogs.zdnet.com/emergingtech/index.php?p=235

this will be the computer

and yes you can veiw your results in full immersive 3d

Alright then no worries, I should generate a file for both Star-CD and Fluent for you to run. Star-CD is a bit complicated! how about Fluent and I send you a little guide on what to do? I will set every boundary condition in advance (say 200 km/hr) like the simulations, all you need to do is press go or Iterate I should say!

Let me know what you think and most importantly what will be your limit on cell count? So that I generate reasonable mesh.

Oh, how on earth do I transfer you the case file? In case of 10 million cells the least, it generates some thing equal to 500MB!

Thanks.

NickT · Post 21 Jun 2006, 14:24

Excellent thread, pictures and explinations. Thanks Guys.

I have a question: If the rear diffuser was limited to a flate plane at an angle of 15deg starting at the centerline of the rear wheels and finishing where the current version ends, would it have a dramatic redution in downforce and the upwash presented to a following car?

I am thinking here of significantly reducing downforce and upwash under the 2008 regulations.