38 replies to this topic

[clipping_point]

A friend of mine perform CFD calculations in Fluent. With a 3D model made in IGES it can be imported to the Fluent program. Has anyone made a 3D model of the VX?? It could be really interesting to simulate some aerodynamic effects.... splitter, side skirts, Exige back....

[clipping_point]

*Knock-knock* Knocking on your screen from the inside Any engineers here??

[Jase_MK]

There's an open source, free car simulation project called "Racer" (http://www.racer.nl/) which I used to mess about with. Users are free to develop their own car models and upload them for others to download. The Opel Speedster 3D model is here:
http://www.racer-xtr...cars.php?ck=141

Now, I have no idea what format that's in (and it also contains other dynamic info such as mass distribution, suspension, tyre friction, etc) but my vague memory of 3D modelling is that there are usually tools out there for converting from one format to another...

Edited by Jase_MK, 27 March 2006 - 04:25 PM.

[Jase_MK]

...

[cyberman]

Just to add to this, has anybody seen or heard of IGES models for the sub-skin stuff? Tub, front and rear frames, suspension, engine / gearbox etc? Even for the S2 Elise would be a good start then we could at least just mod the bits where its different.

[clipping_point]

There's an open source, free car simulation project called "Racer" (http://www.racer.nl/) which I used to mess about with. Users are free to develop their own car models and upload them for others to download. The Opel Speedster 3D model is here:
http://www.racer-xtr...cars.php?ck=141

Great, there has to be a converter somewhere

(nice colour as well! )

[MartinS]

See id anyone has OKINO, Polytrans. It converts nearly everyuthing, and is often incorporated in 3D Max if anyone has that. I do real-time computer garphics but dont use that format. Martin s

[RWinstanley]

I'm a CFD engineer, although i do internal aerodynamics now i was involved in some external aero work (using STAR-CD) To be honest unless he's got access to about a 10 CPU LINUX cluster he's not going to be able to make much progress on solving a full car model as you need around 10 million cells, to captuer the geometry and enough of the wake to calculate the lift. Also to get a good idea of the drag you need to model the radiator compartment as this acts like an airdam. As you say you could use the outline to try different aero options comparativly but this would be very crude analysis which wouldn't be acurate enough to gain anything more that applying fundamentals. But i'll have a look at that file later to see if i can help translate it fro the record an IGES file is a file that gives geometry in the form of point, curves and surfaces. Rob

[mart356]

Then again it could be a kids interpretation of the VX's surfaces not accurate. I'd like a an accurate CAD model of the VX to design a new type of roof (one you can carry a surboard/ skis on - or have it open with lovely aluminium side bars)

[cyberman]

Well, if you find one let me know (and I'll certainly shout if I find one) because I too want to get some stuff drawn which would be facilitated by not having to strip the car and measure everything first.

[jneill]

Has anyone tried asking either Lotus or GM? Many many years ago I wanted to build a rc model of a Short Sunderland so I wrote to Short Brothers in Belfast and blow me if they didn't send me detailed A1 sized plans. Unfortunately lazyness set in so I did nothing with them - and now I can't find them anymore. Bugger.

[jules_s]

>clicky<

at a cost though by the looks of it

[clipping_point]

Wow the $199 one in 3D Max looked amazing, although not perfect!

The $76 one was a complete joke...

As you say you could use the outline to try different aero options comparativly but this would be very crude analysis which wouldn't be acurate enough to gain anything more that applying fundamentals.

My thought was that a relative comparison between the underbody pressure at different ride heights, splitter sizes, impact of vertical level of rear wing could be studied even with a crude model?

[jules_s]

Ive found one

Not sure if he will give it to us.......i think he may be european given his e-mail address?

>clicky<

[cxs]

Hello, I never did CFD simulations, but not only you have the problem of the enormous amount of CPU power to do something interesting, but also, the quality of the car model mesh. The IGES format that you get may have a non-clean geometry, not suited for mesh generation over it...Maybe the software your friend uses does that in a automatic way... Anyway..if something gets out from there I would like to see it. regards...

[RWinstanley]

Modern meshing packages deal with dirty and lazily draw geometry it would be possible to clean it up. However the last one i was involved with, the Proton GEN2 done by my colleague, took about 3 weeks full time to create the mesh (you also need about 4 GB of RAM). Then another 2 days solving. Lotus never did any CFD on either the VX or the Elise but they did CFD to optimise the aerodynamics for the diesel VX record braking car. There is a Fluent paper on it from the User conference. If you want to look at splitter and wing options then should be able to get an idea using a 2D section with out the need for huge computing power.

Edited by RWinstanley, 30 March 2006 - 05:58 PM.

[Ferguson]

Lotus never did any CFD on either the VX or the Elise but they did CFD to optimise the aerodynamics for the diesel VX record braking car. There is a Fluent paper on it from the User conference.
.

> click <

[RWinstanley]

That's only a small summary the real paper is about 8 pages long and goes into the desails of how they optmised the flow, drag and cooling. Notice the nose is more pointed and longer. Also the rad bay shape was changed as well as the position of the rads. I used to have a copy on my desk, it's from one of their european user conferences

[clipping_point]

Ive found one

Not sure if he will give it to us.......i think he may be european given his e-mail address?

>clicky<

He may be sending his model to me. It is made in "Rhinosaurus" which can be converted to IGES. The look is stunning, but the cooler duct is not modelled.

[MartinS]

If you get it, can I have a copy. My job is creating virtual worlds for the military etc and it woujld be good to get a VX into some of the scenarios. I would also be able to try out some ideas for thje car in 3d. Martin s