Elmer validation/limitations

General discussion about Elmer
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Epy
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Elmer validation/limitations

Post by Epy »

Greetings all,

I have two questions:
1) Has Elmer been validated in any way? (physically, numerically, anything)
2) Are there any limitations of Elmer?

I have been using specific codes for specific applications (Code_Aster for solid mechanics, Code_Saturne for fluid mechanics, MATLAB/Octave for other rough simulations) and would like to learn one code (Elmer) to fulfill all my needs. Code_Aster and Code_Saturne are validated by the EDF (see http://cfd.mace.manchester.ac.uk/twiki/ ... in_CFD.pdf for example) so I can feel confident in the results of those codes. So before I switch to Elmer, it would be nice to feel the same confidence. Also, I ask if there are limitations because I want to know if I'll still have to go to another specific code to solve some things if Elmer isn't well equipped enough (e.g. maybe other codes are better suited for high-speed flows, etc.).

Thanks in advance for any comments.
I have also asked this question here: http://caelinux.com/CMS/index.php?optio ... mid=300025
raback
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Re: Elmer validation/limitations

Post by raback »

Hi Jake

Elmer has been verified always when new models have been introduced. The verification may be againts simple analytical solutions, or against results from other codes. The verificiation is not complete in the sense that all possible choices by the user would have been verified. That would probably be impossible but generally also the user is assumed to know what she is doing.

The philosophy of Elmer is quite different from Code_Aster and Code_Saturne since these codes are the backbone of the simulation activity of EDF and verification and validation cannot be taken lightly if you have nuclear power to consider. This on the other hand, makes the codes more stale. It is more difficult to introduce new features upstream in a catheedral type of development model. In Elmer we emphasize agility and strive to have a more bazaar type of development model. Sometimes good ideas are implemented the same day, and people may even be given right to commit code. Combined with the extreme modularity of Elmer I would guess that Elmer is more easily adaptable, but on the other hand, if you're doing what EDF is doing you'll find better validated models there.

It is quite difficult to say that Elmer would not have any limitations. There are so many fields: fluids, structures, electromagnetism, acoustics, transport, etc. Usually people will have some specific field in their mind and do not maybe think of the number of fields. The main strength in Elmer is that these fields may be coupled without an a priori defined way. In individual fields among OS codes OpenFOAM is certainly more able in high Re flows. Elmer excells more in FSI, and recently also perhaps in acoustics and electromagnetism where there are quite modern models. From developers point of view there are actually quite little limitations as you can always write new code, but the time-to-solution may just become impractical if there are existing solutions in some other codes.

-Peter
Epy
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Re: Elmer validation/limitations

Post by Epy »

Thanks for your quick response Peter. It is good to know that Elmer is validated against other solutions, and also to know that it excels in FSI. FSI is probably the main reason I want to use Elmer; a generalized example of what I want to do is heated fluid flow through a pipe while the outside of the pipe is being cooled by ambient. It sounds like Elmer can do that with ease. Thanks!
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