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-   -   what is the number infront of divergence or laplacian scheme in fvSchme? (https://www.cfd-online.com/Forums/openfoam-solving/122172-what-number-infront-divergence-laplacian-scheme-fvschme.html)

s.m August 13, 2013 17:26
what is the number infront of divergence or laplacian scheme in fvSchme?
 
Hi Foamers,
i have a queation that may seems to you very simple!
what is the number infront of divergence or laplacian scheme in fvSchme?
e.g "1.0" in div(phi,U) bounded Gauss GammaV "1.0"
or "0.7" in laplacian(nuEff,U) Gauss linear limited "0.7";
what is them, and what is the effect of the decreasing or increasing them on our analysis?

Thankyou:)

s.m September 15, 2013 03:57
any guidance?:(

wyldckat September 15, 2013 08:49
Greetings s.m,

Quick question: Have you checked the OpenFOAM User Guide? Namely the section 4.4 Numerical schemes?

There is also the Programmer's Guide, where you can find additional information. The following page provides information on where to find it and includes some corrections to this guide: http://openfoamwiki.net/index.php/Op...s_Guide_Errata

Best regards,
Bruno

s.m September 15, 2013 11:22
Quote:
Originally Posted by wyldckat (Post 451804)
Greetings s.m,

Quick question: Have you checked the OpenFOAM User Guide? Namely the section 4.4 Numerical schemes?

There is also the Programmer's Guide, where you can find additional information. The following page provides information on where to find it and includes some corrections to this guide: http://openfoamwiki.net/index.php/Op...s_Guide_Errata

Best regards,
Bruno
Hi
yes, but i can't understand the role of the number 1.0 or 0.33 or 0.7 that is written in front of the scheme!

wyldckat September 15, 2013 15:37
If I'm not mistaken, it's the values explained in section "4.4.2 Surface normal gradient schemes".

I forgot to mention this reference wiki page as well: http://openfoamwiki.net/index.php/OpenFOAM_guide - be sure to read the pages therein.

Sorry that I don't have a clear answer for you, but this is just to help you find some more sources of information, until someone who knows the answer can write about it :( Because I don't know the exact answer you're looking for.

And I do have the feeling that this has already been on the forum already...

Good luck!
Bruno

Tobi September 15, 2013 15:37
In the numerical schemes with limiter its the functionallity of it like:

Code:
1 = limiter function to 100%
0.33 = limiter function to 33 %
0 = limiter function 0 %
therefor the scheme

Code:
Gauss limitedLinear 0
should be the same as
Code:
Gauss linear
I think in the laplacian scheme its something like this, isn't it?

s.m September 16, 2013 15:47
Quote:
Originally Posted by Tobi (Post 451852)
In the numerical schemes with limiter its the functionallity of it like:

Code:
1 = limiter function to 100%
0.33 = limiter function to 33 %
0 = limiter function 0 %
therefor the scheme

Code:
Gauss limitedLinear 0
should be the same as
Code:
Gauss linear
I think in the laplacian scheme its something like this, isn't it?
Thank you Tobi,
in laplacian scheme is "Gauss linear limited 1.0"
what is this limiters do when we set the laplacian scheme set to use them?
in oder words, is it better to use Gauss linear that doen't use any limiters or it is good to use limiters, why?
Thank you for your guidance.:o


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