Khamsin Virtual Racecar Challenge 2015

[CAEdevice]

hi guys, there is no need to release the car: I was just curious about the test car (in the images published on the kvrc website there is a report: are that numbers referred to the test car?).

As Julien wrote, now that OCCFD has been released there is no need of a test car to calibrate our systems.

About the CPU power: I have an old workstation that is enough powerful to be used with Openfoam, also during kvrc: the problem is that I'm a partecipant to the challange, so I should not manage other cars.

[CAEdevice]

@Julien

Code: Select all

C:\Programmi\ImageMagick-6.
9.0-Q16\convert frontalArea1.bmp -format info:
convert.exe: missing an image filename `info:' @ error/convert.c/ConvertImageCom
mand/3207.

You can see also the directory where ImageMagik is installed.

EDIT: Problem solved. I'm quite sure that the problem was related to both my geoemtry e my ImageMagik Installation (X64 and not x86). Thanks for your help!

[CAEdevice]

Here are some questions about the geometry file to submit:

1) Are the wheels to be submitted? In the rulbook it seems that they are not to be included
2) The inlet/outlet surfaces have to be detached from the body or they cab be copied from the body? ( = the body will be a solid or a surface with the holes of the cutted surfaces? SimpleFoam seeems to work in both cases, but I don't know if the results are right)
3) Suspensions beams should be included in the geoemtry?

[cdsavage]

Here are some questions about the geometry file to submit:

1) Are the wheels to be submitted? In the rulbook it seems that they are not to be included
2) The inlet/outlet surfaces have to be detached from the body or they cab be copied from the body? ( = the body will be a solid or a surface with the holes of the cutted surfaces? SimpleFoam seeems to work in both cases, but I don't know if the results are right)
3) Suspensions beams should be included in the geoemtry?

In the RC2 rulebook, this is all covered by K1.4, K1.5 and K1.6. Suspension and wheels should not be submitted, and for now we are asking that the separate parts be split off from each other, so that they are surfaces which would form a solid if joined back together.

[CAEdevice]

Here are some questions about the geometry file to submit:

1) Are the wheels to be submitted? In the rulbook it seems that they are not to be included
2) The inlet/outlet surfaces have to be detached from the body or they cab be copied from the body? ( = the body will be a solid or a surface with the holes of the cutted surfaces? SimpleFoam seeems to work in both cases, but I don't know if the results are right)
3) Suspensions beams should be included in the geoemtry?

In the RC2 rulebook, this is all covered by K1.4, K1.5 and K1.6. Suspension and wheels should not be submitted, and for now we are asking that the separate parts be split off from each other, so that they are surfaces which would form a solid if joined back together.

Thanks!

[Sabino]

Hi Guys, im new here and this is slightly offtopic,

About that one click cfd (occfd) would you consider this professional cfd software?
Right now im using autodesk flow design cause its so easy, anybody knows if this is any good? im a designer, not an engineer at all but i just love this cfd stuff, really want to learn it.

Here's an example of what i did, i really dont know how accurate this is,...

[Daliracing]

Hi Guys, im new here and this is slightly offtopic,

About that one click cfd (occfd) would you consider this professional cfd software?
Right now im using autodesk flow design cause its so easy, anybody knows if this is any good? im a designer, not an engineer at all but i just love this cfd stuff, really want to learn it.

Here's an example of what i did, i really dont know how accurate this is,...

https://www.youtube.com/watch?v=VKiYEXLkJ0k

Hi could it be i saw this car on Behance? i really liked the design of it!

[RicME85]

OCCFD isn't proper piece of CFD software, its a few batch files which bring together various software (openfoam, paraview, etc) to produce the results that a piece of pro software would do on its own.

[CAEdevice]

Hi Guys, im new here and this is slightly offtopic,

About that one click cfd (occfd) would you consider this professional cfd software?
Right now im using autodesk flow design cause its so easy, anybody knows if this is any good? im a designer, not an engineer at all but i just love this cfd stuff, really want to learn it.

Here's an example of what i did, i really dont know how accurate this is,...

https://www.youtube.com/watch?v=VKiYEXLkJ0k

Great car and great post processing.

I think that with Paraview (included in the OCCFD installation) you could obtain about the same.
https://www.youtube.com/watch?v=XqZ85TRubbY
Julien produced some impressive post processing importing the results contour to blender.

I'm using a commercial package too (toghether with OCCFD/OpenFoam), and I think you should consider also:

Price: Commercial CFD package costs from 20k€/$ to 40k€/$, OpenFoam and Paraview are free (even open source), OCCFD is reserved to KVRC patecipants, but its predecessor was nearly (the cost was very small) free.

Solver variety: being OpenFoam based, OCCFD can run different kind of solver with small tweaks (http://www.openfoam.org/features/standard-solvers.php) and easily creates new ones (someone used it to study cells reproduction or the negative effects of keynesian economics!).

OCCFD and commercial codes have different approaches and they fields don't overlap compeltely.

[Sabino]

Hi Guys, im new here and this is slightly offtopic,

About that one click cfd (occfd) would you consider this professional cfd software?
Right now im using autodesk flow design cause its so easy, anybody knows if this is any good? im a designer, not an engineer at all but i just love this cfd stuff, really want to learn it.

Here's an example of what i did, i really dont know how accurate this is,...

https://www.youtube.com/watch?v=VKiYEXLkJ0k

Hi could it be i saw this car on Behance? i really liked the design of it!

Yes thats right, but i want a more professional approach in car design and since i love fast cars, cfd is getting more and more important,

RicME85, thats all fine by me, i just want to know how accurate these results are, if it uses a batch im perfectly fine with that.
Autodesk themselves say flow design isnt professional cfd, yet in the pdf provided they do compare it with professional cfd packages and how close it is to those so its confusing, was just wondering if some people have experience with it?

CAEdevice, the post processing is actually standard in autodesk flow design, you have a bunch of settings you can chose from.
A Commercial CFD package is way out of my budget tbh, thats why i have flowdesign for now, its only 200per year orso, but again, nut sure how thrustworthy these results are.

Another thing, how hard is it to learn this OpenFoam, does it require a phd or would some tutorials basically do the trick?...

[julien.decharentenay]

OCCFD is reserved to KVRC participants.

The above is not quite correct. OCCFD can be used by anyone, including KVRC participants. There is no cost, no license, no registration. Download and use.

As mentioned OCCFD is a few scripts put together to turn a bunch of open-source software into something that is dedicated to car aerodynamic. The underlying CFD solver, openFoam, can be quite accurate, is used by industry and is supposed to be comparable to a generic CFD software - just: it does not come with the price tag, easy installation, GUI and support.

OCCFD assumes a number of meshing strategies and physical models that are not "best-in-class". As an example, the mesh size is typically in the order to 2 Millions cells with OCCFD, whereas a full blown accurate CFD model for a racing car is more in the order of 100 millions cells. Obviously it has an impact on accuracy...

Is OCCFD more accurate that Autodesk simulation tool? You could have a look at comparing on a couple of benchmarks and assess how it works. One small aspect is that OCCFD extracts COP and distibution of downforce and drag, which I do not think Autodesk does.

[CAEdevice]

Sorry Julien, my fault. With the word "reserved to" I meant "dedicated to".
OCCFD is free and very promising.

[Sabino]

OCCFD is reserved to KVRC participants.

The above is not quite correct. OCCFD can be used by anyone, including KVRC participants. There is no cost, no license, no registration. Download and use.

As mentioned OCCFD is a few scripts put together to turn a bunch of open-source software into something that is dedicated to car aerodynamic. The underlying CFD solver, openFoam, can be quite accurate, is used by industry and is supposed to be comparable to a generic CFD software - just: it does not come with the price tag, easy installation, GUI and support.

OCCFD assumes a number of meshing strategies and physical models that are not "best-in-class". As an example, the mesh size is typically in the order to 2 Millions cells with OCCFD, whereas a full blown accurate CFD model for a racing car is more in the order of 100 millions cells. Obviously it has an impact on accuracy...

Is OCCFD more accurate that Autodesk simulation tool? You could have a look at comparing on a couple of benchmarks and assess how it works. One small aspect is that OCCFD extracts COP and distibution of downforce and drag, which I do not think Autodesk does.

Ok, i havent tried it yet cause i need to install a list of other software right? and why did you (its your software right if i read correctly?) go for 2 million cells max? and while were at it is there a vast difference between ie. 20 million cells 50 million cells and 100 million cells results? Right now with the autodesk flow design i can get the mesh size somewhere around 0.03 i think max and thats it, it does however show surface pressure and drag but again, not sure how accurate this all is, i really have my doubts.

If i go too much offtopic, sorry about that,...

[MadMatt]

You can check a recent thread of mine about number of cells VS results: http://www.f1technical.net/forum/viewto ... =6&t=21502

[julien.decharentenay]

Ok, i havent tried it yet cause i need to install a list of other software right? and why did you (its your software right if i read correctly?) go for 2 million cells max? and while were at it is there a vast difference between ie. 20 million cells 50 million cells and 100 million cells results?

There is a number of software to install. If they are not installed (or not installed in the right places), you will receive an error when running OCCFD. The list of software is available at: http://www.khamsinvirtualracecarchallen ... -click-cfd.

It is roughly around 2 million cells. The reason is that OCCFD is focused on the KVRC challenge. As we (organiser of the challenge) are running the CFD simulation on the submitted cars, we need to keep an eye on how long these take (and hence cost). So it is a trade-off between mesh size and time/cost... 2 million seems around reasonable, as it enables as a resolution of around 8mm at the body and 4mm at the wings...

I could look at a as refined as you can option...