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-   -   Experiences with OpenFOAM and Automobile External Aero (http://www.cfd-online.com/Forums/openfoam/84164-experiences-openfoam-automobile-external-aero.html)

kyle January 21, 2011 13:15

Experiences with OpenFOAM and Automobile External Aero
 
Would anyone be willing to share their experiences using OpenFOAM for automobile aero or underhood simulations? I have been evaluating this software for the better part of two months trying to get a feel for if we can replace Star-CCM+. Everything works great on our validation cases, but more complex geometry is troublesome. SnappyHexMesh is working for me very well. The mesh is at least as good at what I can get out of CCM+ and can be generated an order of magnitude faster. I can get very good results with simpleFoam and kOmega SST, but my main gripe is that I end up babysitting every run to convergence. I have to fiddle with solver settings and monitor max values for U/p/k and remove cells as they get out of control before they pollute the entire simulation. Any fvSolution/fvSchemes combination I get to work with one mesh seems to immediately diverge on the next mesh, no matter how similar the mesh.

I have spoken with engineers at other companies that have very robust OpenFOAM setups, but of course they were unable to give me any detailed information on how they got to that point. I am hoping someone here is able to share a little more. I'd love to hear about different workflows that are being used successfully and if possible even see some fvScheme/fvSolution/snappyHexMeshDict/other files that are being used in the wild. Failing that just let me know whether or not I have unrealistic expectations of this software!

Thanks for any information you can provide!

Ralph M January 25, 2011 08:30

Hello Kyle,

Since a few weeks I've doing some aero calculations for a car (corvette C6). I'm using simplefoam with a mesh from SHM. Still in the phase of semi-2D but planning to go 3D next week. I'm willing to share the input files; I'll try to put them on this forum tonight.

Right now I'm exploring the possibilities for the 3D calculation; would it be possible to model the grill as a semi porous surface for example?

Cheers,

Ralph

kyle January 25, 2011 12:55

Ralph,

Thanks for your reply. I have not gotten to this point yet, but I was planning on using a thin porous volume for the grill. This is my usual approach because unstructured mesh generators are usually not very well suited for creating a zero thickness wall within one volume. Anyway, I don't believe the OpenFOAM solver itself has support for porous walls without some sort of kludge using a cyclic boundary.

Kyle

leinadpm January 27, 2011 12:26

snappyHexMesh prism layer problem
 
Hi,

I'm using snappyHexMesh (sHM) to generate the grid around a formula car wing, I tried a lot ways to make sHM to produce a continuous prims layer but I could not. So if anyone knows which of the sHM dictionary parameters can be modified to achieve that I'll be very grateful.

Thanks
http://i1220.photobucket.com/albums/.../ZoomLayer.jpg
http://i1220.photobucket.com/albums/...m/WingMesh.jpg

jonbonraki May 31, 2013 21:40

Quote:

Originally Posted by Ralph M (Post 292067)
Hello Kyle,

Since a few weeks I've doing some aero calculations for a car (corvette C6). I'm using simplefoam with a mesh from SHM. Still in the phase of semi-2D but planning to go 3D next week. I'm willing to share the input files; I'll try to put them on this forum tonight.

Right now I'm exploring the possibilities for the 3D calculation; would it be possible to model the grill as a semi porous surface for example?

Cheers,

Ralph

hi ralph i m doing an aero calucaltions for my project to reduce drag in suv, ur inputs file will be much appreciated, if your willing to share it would be really great raj123om@gmail.com

patiltushar123 October 24, 2013 06:52

car OPENfoam
 
hello,
u can create bl around any surface in shm, use one of foll:

> try and create bl's less than 7( this is weird, but true)
> try and use foam 2.2.x
With this two, i m sure it will work!

Also, u can try changing the face angle (default 150 deg)


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