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-   -   problem with an upwind div scheme (http://www.cfd-online.com/Forums/openfoam-solving/119049-problem-upwind-div-scheme.html)

giack May 30, 2013 13:26

problem with an upwind div scheme
 
Hi to all,I have a problem with an upwind div scheme

I set this scheme:
divSchemes
{
div(rho*phi,U) Gauss linearUpwindV cellLimited Gauss linear 1;
div(phi,alpha) Gauss vanLeer;
div(phirb,alpha) Gauss interfaceCompression;
}

the simulation is good but in my log file there is the following warming message:
--> FOAM Warning :
From function linearUpwindV(const fvMesh&, const surfaceScalarField& faceFlux, Istream&)
in file interpolation/surfaceInterpolation/schemes/linearUpwind/linearUpwindV.H at line 153
Reading "/home/giacomo/Scrivania/20x20x500UP/processor0/../system/fvSchemes::divSchemes::div(rho*phi,U)" at line 30
unexpected additional entries in stream.
Only the name of the gradient scheme in the 'gradSchemes' dictionary should be specified.

It have influence on simulation?
Another question: I would discretize all U terms with an upwind scheme. So i would choose an upwind scheme for the term grad(U) but I obtain an error message and the simulation don't start...How I can set an upwind scheme also for grad(U)

thank to all

wyldckat June 8, 2013 18:11

Greetings giack,

This isn't my field of expertise, but the following line is clearly wrong:
Code:

div(rho*phi,U)  Gauss linearUpwindV cellLimited Gauss linear 1;
If I'm not mistaken, if should be something like:
Code:

div(rho*phi,U)  Gauss linearUpwind grad(U);
at least based on what I've seen in tutorials...

You can find more examples, by running:
Code:

find $FOAM_TUTORIALS -name "fvSchemes" | xargs grep "grad(U);"
If you want to change how "grad(U)" is done, should add the entry to the "gradSchemes" block:
Code:

gradSchemes
{
    default        Gauss linear;
    grad(U)        cellLimited Gauss linear 1;
}

Best regards,
Bruno

giack June 8, 2013 18:30

thank you for your relpy.
I already tried your last advice but I have another error and simulation don't start. This is a very strange case.
Moreover I find that with the istruction
div(rho*phi,U) Gauss linearUpwindV cellLimited Gauss linear 1;
OF neglect the command and choose the default value for gradScheme required in the div term. So i use the following line:
div(rho*phi,U) Gauss linearUpwindV default;
I think that there aren't a lot of differences beetwen two gradSchene,it's true?

Tushar@cfd June 21, 2013 01:25

Quote:

Originally Posted by giack (Post 432833)
thank you for your relpy.
I already tried your last advice but I have another error and simulation don't start. This is a very strange case.
Moreover I find that with the istruction
div(rho*phi,U) Gauss linearUpwindV cellLimited Gauss linear 1;
OF neglect the command and choose the default value for gradScheme required in the div term. So i use the following line:
div(rho*phi,U) Gauss linearUpwindV default;
I think that there aren't a lot of differences beetwen two gradSchene,it's true?


Are you able to solve your problem?
Try the scheme limitedLinear and do let us know about the results.

:)

giack June 21, 2013 04:26

Hi,
at this time I'm simulating two case: one with limetedLinearV 1 and the other with linearUpwindV Gauss linear. Simulations are not over yet but when they end I post my results.


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