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-   -   linearUpwind scheme in OpenFOAM 2.0.1 ??? (http://www.cfd-online.com/Forums/openfoam/92351-linearupwind-scheme-openfoam-2-0-1-a.html)

cabul September 12, 2011 04:24

linearUpwind scheme in OpenFOAM 2.0.1 ???
 
Hello FOAMers,
i just wanted to set up a new simulation an user the following schemes:
Quote:

divSchemes
{
default none;
div(phi,U) Gauss linearUpwindV cellLimited Gauss linear 1;
div(phi,k) Gauss linearUpwind cellLimited Gauss linear 1;
div(phi,epsilon) Gauss linearUpwind cellLimited Gauss linear 1;
div(phi,R) Gauss linearUpwind cellLimited Gauss linear 1;
div(nonlinearStress) Gauss linearUpwind cellLimited Gauss linear 1;
div(R) Gauss linearUpwind cellLimited Gauss linear 1;
div(phi,nuTilda) Gauss linearUpwind cellLimited Gauss linear 1;
div((nuEff*dev(T(grad(U))))) Gauss linearUpwind cellLimited Gauss linear 1;
}
but i ended up with the following message:

Quote:

--> FOAM FATAL IO ERROR:
Unknown discretisation scheme linearUpwind

Valid schemes are :

41
(
Gamma
MUSCL
Minmod
OSPRE
QUICK
SFCD
SuperBee
UMIST
biLinearFit
blended
clippedLinear
cubic
cubicUpwindFit
downwind
filteredLinear
filteredLinear2
filteredLinear3
fixedBlended
limitWith
limitedCubic
limitedLinear
limiterBlended
linear
linearFit
linearPureUpwindFit
localBlended
localMax
localMin
midPoint
outletStabilised
pointLinear
quadraticFit
quadraticLinearFit
quadraticLinearUpwindFit
quadraticUpwindFit
reverseLinear
skewCorrected
upwind
vanAlbada
vanLeer
weighted
)


file: ./S-0.00/system/fvSchemes::divSchemes::div((nuEff*dev(T(grad(U)))) ) at line 40.

From function surfaceInterpolationScheme<Type>::New(const fvMesh&, Istream&)
in file lnInclude/surfaceInterpolationScheme.C at line 82.

FOAM exiting
Is there a new name for the linearUpwind scheme or has it been removed? I am quite new to OpenFOAM so maybe i made a mistake myself. Can Anyone help me?

Greeting,s
André

cabul September 13, 2011 03:59

Does nobody have the same Problem?

cabul September 13, 2011 07:00

Hello there,

i played around with the fvSchemes for a while and ended up with the following settings, that are working for me.

Quote:

gradSchemes
{
default cellLimited Gauss linear 1;
}

divSchemes
{
default none;
div(phi,U) Gauss linearUpwindV default;
div(phi,k) Gauss linearUpwind default;
div(phi,epsilon) Gauss linearUpwind default;
div(phi,omega) Gauss linearUpwind default;
div(R) Gauss linear;
div((nuEff*dev(T(grad(U))))) Gauss linear;
}
Can somebody have a look at the divschemes? As far as i understood OpenFOAM 2.0.1 checks for an gradShemes right behind the definition "Gauss linearUpwind" . Is it correct to set the "default" value here, so that it uses the "cellLimited Gauss linear 1" -scheme, defined in gradSchemes?

as mentioned before, the calculation is running fine and the results look good too.

Greetings,
André

idrama September 13, 2011 10:37

In OF-2 I use linearUpwind(V) in this way:

div(phi,U) Gauss linearUpwindV grad(U);
dib(phi,k) Gauss linearUpwind grad(k);

and so on.

Cheers

fisch November 7, 2011 14:05

Hello,

could someome tell me what the meaning of this grad(U) in the div(phi,U) discretization is?
Thanks

rupert

eugene November 8, 2011 06:19

Quote:

Originally Posted by fisch (Post 331079)
Hello,

could someome tell me what the meaning of this grad(U) in the div(phi,U) discretization is?
Thanks

rupert

It tells you which gradient scheme to use for the gradient part of the LUD discretisation. The specific gradient scheme is defined in the gradSchemes section. So you do not have to use "grad(U)", you can use anything you like as long as it is defined in the gradSchemes section. E.g.

gradSchemes
{
blahblahblah Gauss linear;
}

divSchemes
{
div(phi,U) Gauss linearUpwindV blahblahblah;
}

should work just fine. In all cases things like "div(phi,U)" and "grad(U)" are just identifiers, thy have no special structure or significance outside this.

fisch November 8, 2011 06:46

Thanks for the answer eugene.

now arise two questions:
1.so it should be the same as the gradient in the implicit field in the div-term?
2. what happens then if i dont specify this: just like div(phi,U) Gauss linear?

thanks a lot

eugene November 9, 2011 06:39

1. As far as I know there is no fixed rule about the nature of the gradient portion of a LUD scheme. Its not like pressure and velocity flux interpolation that has to be consistent.
2. If you don't specify anything at all, the code should crash (or maybe not, I haven't checked). If you specify something with no match in the gradScemes section, it should use the "default" gradScheme entry without complaint. If no default entry is present, it should exit with an error.

fisch November 9, 2011 07:57

thank you eugene


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