flow over cylinder
 

Hi
i am working on flow past cylinder with Re=0 ,i attached geometry .there are no require set pressure boundary at AB and BC ,how can i implement it in 0/p?i set it as below but no working fine.please help


/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.2.2 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -2 0 0 0 0];

internalField uniform 1;

boundaryField
{
left
{
type symmetryPlane;
}

right
{
type fixedValue;
value uniform 0;
}

down
{
type symmetryPlane;
}

up
{
type zeroGradient;
}

cylinder
{
type zeroGradient;
}

frontAndBack
{
type empty;
}
}


/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.2.2 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volVectorField;
object U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);

boundaryField
{
left
{
type symmetryPlane;

}

right
{

type fixedValue;
value uniform (0 1 0);
}

down
{
type symmetryPlane;

}

up
{
type fixedValue;
value uniform (0 1 0);
}

cylinder
{
type fixedValue;
value uniform (0 0 0);
}

frontAndBack
{
type empty;
}
}

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.2.2 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
p
{
solver GAMG;
tolerance 1e-6;
relTol 0;
smoother GaussSeidel;
nPreSweeps 2;
nPostSweeps 2;
cacheAgglomeration on;
agglomerator faceAreaPair;
nCellsInCoarsestLevel 10;
mergeLevels 1;
}

U
{
solver smoothSolver;
tolerance 1e-6;
relTol 0;
smoother GaussSeidel;
}
}

SIMPLE
{
nNonOrthogonalCorrectors 0;
pRefPoint (2,0,0);
pRefCell 0;

residualControl
{
p 1e-3;
U 1e-4;
}
}

relaxationFactors
{
fields
{
p 0.3;
}
equations
{
U 0.7;
}
}

Hi,

I am not sure what you mean by Re=0. So there is no flow at all?

Can please provide an error message or what exactly is not working?

On the right hand side you have a symmetry wall, yet you want a flow perpendicular to it? I do not think thats physically possible. Correct me if I am wrong, by in a symmetry plane the mass-flow should be 0 and thus the stream lines need to parallel to the surface, otherwise you have a line with mass constantly flowing in from both sides. Where is the fluid supposed to go without removing mass or compressing it to infinity?

Dear
there was some mistake in the picture,i changed it.
the flow is non-newtonnian (creeping flow like foams , filled polymer solution ) therefore re<<1, i attached the governing equations .the problem considered with two planes of symmetry, hence one quater of the domain is used,also i attached the all domain.
Thanks

Hi all,

• first I did not check you first post because there are missing code-tags.
• out of the last post, you have to implement a few stuff yourself.
• I am not sure if eqn. 9 and 10 are correct (you should derive this yourself to be sure).
• If the viscosity model is not implemented in foam, you have to implement it yourself.
• based on your domain, you need to set the pRefValue in fvSolutions. Otherwise it will not work because you are not defining a well constrained problem.

Finally it is exact that one here: http://www.holzmann-cfd.de/index.php...gelumstroemung
But in your case it is a non-newtonian flow. Based on the tensors and fluid behaviors, maybe you are allowed to simplify the deviatoric stress tensor to get a Poisson equation but maybe it is not possible. Anyway (:

Dear Tobi
I attach the domain ,I dont want to apply pressure boundary condition at AB(up) and BC (right) ,how can i do it in the codes?

object p;

boundaryField
{
left
{
type symmetryPlane;
}

right
{
?????????????what should i write???
}

up
{
?????????????what should i write???
}
.
...

First guess,

• right -> p :: zeroGradient

• up -> p :: zeroGradient

set the refPressure close to the symmetry point and try.

PS: I am not sure if you can simplify the case in that way. It should be wrong if I think about it. You should have 2 symmetryPlanes but could it be that you have 3. ?