Numerical schemes: under the hood
 

Dear foamers,

I am interested in finding out how the different numerical schemes available in OpenFOAM work.

I would like to understand some details. Is there any documentation available and/or which are the files in the src where they are expliceted?

Thanks a lot,
Samuele

Hi,

you can browse the doxygen http://www.openfoam.org/docs/cpp/
http://foam.sourceforge.net/docs/cpp...c3619d681.html might be what you looking for

Thanks Elvis,

that's could be a good starting point. Also, do you know if a more `theoretical' documentation exists?

Thanks,

Samuele

And how can I understand which is the best numerical scheme for each solver?

Thanks again,
Samuele

Any textbook on CFD will give information on numerical scheme and how they are defined and can be related to stability and stuff like that.

Which schemes you should use depends on the case more than the solver.

Dear Bernhard,

thanks for answering.

Actually, I agree when you say that I should read a book about Fluiddynamycs.

The point is that I would like to find a book which uses the names used by OF. For example, reading here, if I have to solve a laplacian I can write:

laplacian(nu,U) Gauss <interpolationScheme> <snGradScheme>

What I would like to und is what is it meant by <interpolationScheme> and by <snGradScheme>.

Could you give me a brief explanation? Or a link?

Thanks a lot.

Samuele

Hi,

if you take a look at the PHD thesis collection from Dr. Jasak http://powerlab.fsb.hr/ped/kturbo/OpenFOAM/docs/ you find OF based/releated CFD-reseach, but the syntax is not source code like you could find s.th. like that in the OF wiki but those Documentations are hiden somewhere in the wiki. Holger Marschall had a docu project in mind, but he was stopped by somebody´s lawyers (who owns a copyright.)

you know Hakan´s Stuff allready?
http://www.tfd.chalmers.se/~hani/kurser/OS_CFD_2011/
..2007

or the Gothenburg OpenFOAM workshop Penn State OF Workshop training Summerschool stuff etc.

Hi Elvis,

thanks for help.

Actually, I am finding out something very interesting.

I have a questio: do you know why the `linear' interpolation scheme is a second order scheme?

Being linear, shouldn't it be first order?

Hello Samuele,

this post is almost 5 years old. but i am new to openfoam. i also have the same question.
i.e. complete description of fvSchemes in OpenFoam terms (well documented).

(I read the Elvis's suggestions as well in the thread)

have u found any ? if yes, can you please paste the link or share any material over the email ?

Hi,
there is a very slooowly improving initiative
http://www.cocoons-project.org/ The goal of the CoCoons Project is to provide peer and technical reviewed, high-quality documentation of C++ libraries for Computational Continuum Numerics on Arbitrary Unstructured Meshes in the Open Source Spirit (OSS).

Asking your Question at the http://www.extend-project.de/ =>OpenFOAM Community (OF-extend people) might lead to some information.

http://www.sourceflux.de/book/

thanks for the suggestion elvis :)

Hey everyone

I try to find an explantation to the fv-schemes.
I shortly searched on the pages elvis suggested, but there is so much information on that many pages that I just don´t know where to start to find the information about the schemes.

I know how to use the main schemes. But I like to understand all schemes from this list.

https://docs.google.com/document/d/1...it?usp=sharing


Best regards Tobi

Edit of above
 

Hmm,
I cannot edit the post!?
Maybe cfd-online does not work very well with google chrome?
EDIT:
Right link to the list of schemes I´m interested in:

https://docs.google.com/document/d/1...it?usp=sharing

best regards Tobi

Hİ tobias
I am laso trying to find an explantation to the fv-schemes. Did you find anything useful.

Best

Dear Muhmt,

please read the notes from Elvis. There you will find all the necessary information. If you want to have all informations, use Doxygen and analyze the C++ code. As it is already written above:

• Schemes are related to numerical mathematics and not OpenFOAM, so you will find everything in books or other documentation
• Based on the fact that I am replying here... the linear scheme is a second order one
• Documentation about schemes can be found in Ferziger - Perić
• After you know the meaning of the schemes (discretization) you probably understand each scheme
• Google is your friend (http://bfy.tw/9ot0)
• And the schemes you use should be related to the problem, e.g. you would never use an Euler time discretization for solving the chemistry

Good luck

Refer the following article on implementation of numerical schemes in OpenFOAM:

http://www.sciencedirect.com/science...95034917300077