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-   -   Extrusion with OpenFoam problem No. Iterations 0 (http://www.cfd-online.com/Forums/openfoam/87126-extrusion-openfoam-problem-no-iterations-0-a.html)

Lord Kelvin April 12, 2011 06:50

Extrusion with OpenFoam problem No. Iterations 0
 
Hi, I'm trying to simulate a laminar flow in a cylinder (hole of the extrusion die) with inlet and outlet (bases) and wall (lateral). I modeled it with Salome 5 (CAE linux) and exported the mesh in UNV.

I post the files:

RaspProperties



/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.7.0 |
| \\ / A nd | Web: www.OpenFOAM.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "constant";
object RASProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

RASModel laminar;

turbulence off;

printCoeffs on;


// ************************************************** *********************** //



transportProperties




/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.7.0 |
| \\ / A nd | Web: www.OpenFOAM.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "constant";
object transportProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

transportModel powerLaw;

nu nu [ 0 2 -1 0 0 0 0 ] 1e-05;

powerLawCoeffs
{
k k [0 2 -1 0 0 0 0] 2800;
n n [0 0 0 0 0 0 0] 0.4;
nuMin nuMin [0 2 -1 0 0 0 0] .1;
nuMax nuMax [0 2 -1 0 0 0 0] 1000000;
}

CrossPowerLawCoeffs
{
nu0 nu0 [ 0 2 -1 0 0 0 0 ] 1e-06;
nuInf nuInf [ 0 2 -1 0 0 0 0 ] 1e-06;
m m [ 0 0 1 0 0 0 0 ] 1;
n n [ 0 0 0 0 0 0 0 ] 1;
}

BirdCarreauCoeffs
{
nu0 nu0 [ 0 2 -1 0 0 0 0 ] 1e-06;
nuInf nuInf [ 0 2 -1 0 0 0 0 ] 1e-06;
k k [ 0 0 1 0 0 0 0 ] 0;
n n [ 0 0 0 0 0 0 0 ] 1;
}

// ************************************************** *********************** //






p









/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.7.0 |
| \\ / A nd | Web: www.OpenFOAM.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [0 2 -2 0 0 0 0];

internalField uniform 0;

boundaryField
{
inlet
{
type zeroGradient;
}

outlet
{
type fixedValue;
value uniform 0;
}

wall
{
type zeroGradient;
}
}

// ************************************************** *********************** //






U







/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.7.0 |
| \\ / A nd | Web: www.OpenFOAM.com |
| \\/ 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
{
inlet
{
type fixedValue;
value uniform (.016 0 0);
}

outlet
{
type zeroGradient;
}

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

// ************************************************** *********************** //






fvSchemes




/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.7.0 |
| \\ / A nd | Web: www.OpenFOAM.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
default Euler;
}

gradSchemes
{
default Gauss linear;
grad(p) Gauss linear;
grad(U) Gauss linear;
}

divSchemes
{
default none;
div(phi,U) Gauss upwind;
div(phi,k) Gauss upwind;
div(phi,epsilon) Gauss upwind;
div(phi,R) Gauss upwind;
div(R) Gauss linear;
div(phi,nuTilda) Gauss upwind;
div((nuEff*dev(grad(U).T()))) Gauss linear;
}

laplacianSchemes
{
default none;
laplacian(nuEff,U) Gauss linear corrected;
laplacian((1|A(U)),p) Gauss linear corrected;
laplacian(DkEff,k) Gauss linear corrected;
laplacian(DepsilonEff,epsilon) Gauss linear corrected;
laplacian(DREff,R) Gauss linear corrected;
laplacian(DnuTildaEff,nuTilda) Gauss linear corrected;
}

interpolationSchemes
{
default linear;
interpolate(U) linear;
}

snGradSchemes
{
default corrected;
}

fluxRequired
{
default no;
p ;
}


// ************************************************** *********************** //






then I run simpleFoam in the directory of the simulation that I created and this is the results:


[...............]




Time = 979

DILUPBiCG: Solving for Ux, Initial residual = 1.23786e-16, Final residual = 1.23786e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.12365e-16, Final residual = 1.12365e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.22862e-16, Final residual = 1.22862e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30448e-08
ExecutionTime = 4.93 s ClockTime = 9 s

Time = 980

DILUPBiCG: Solving for Ux, Initial residual = 1.26725e-16, Final residual = 1.26725e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.12963e-16, Final residual = 1.12963e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.21408e-16, Final residual = 1.21408e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30457e-08
ExecutionTime = 4.94 s ClockTime = 9 s

Time = 981

DILUPBiCG: Solving for Ux, Initial residual = 1.23068e-16, Final residual = 1.23068e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.11831e-16, Final residual = 1.11831e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.23645e-16, Final residual = 1.23645e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30465e-08
ExecutionTime = 4.94 s ClockTime = 9 s

Time = 982

DILUPBiCG: Solving for Ux, Initial residual = 1.26931e-16, Final residual = 1.26931e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.0935e-16, Final residual = 1.0935e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.22962e-16, Final residual = 1.22962e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30474e-08
ExecutionTime = 4.95 s ClockTime = 9 s

Time = 983

DILUPBiCG: Solving for Ux, Initial residual = 1.23579e-16, Final residual = 1.23579e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.15394e-16, Final residual = 1.15394e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.2132e-16, Final residual = 1.2132e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30483e-08
ExecutionTime = 4.96 s ClockTime = 9 s

Time = 984

DILUPBiCG: Solving for Ux, Initial residual = 1.26194e-16, Final residual = 1.26194e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.08941e-16, Final residual = 1.08941e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.23718e-16, Final residual = 1.23718e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30491e-08
ExecutionTime = 4.96 s ClockTime = 9 s

Time = 985

DILUPBiCG: Solving for Ux, Initial residual = 1.23803e-16, Final residual = 1.23803e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.12121e-16, Final residual = 1.12121e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.22867e-16, Final residual = 1.22867e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.305e-08
ExecutionTime = 4.96 s ClockTime = 9 s

Time = 986

DILUPBiCG: Solving for Ux, Initial residual = 1.26728e-16, Final residual = 1.26728e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.12798e-16, Final residual = 1.12798e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.21437e-16, Final residual = 1.21437e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30508e-08
ExecutionTime = 4.96 s ClockTime = 9 s

Time = 987

DILUPBiCG: Solving for Ux, Initial residual = 1.23051e-16, Final residual = 1.23051e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.11958e-16, Final residual = 1.11958e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.23644e-16, Final residual = 1.23644e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30517e-08
ExecutionTime = 4.97 s ClockTime = 9 s

Time = 988

DILUPBiCG: Solving for Ux, Initial residual = 1.26928e-16, Final residual = 1.26928e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.09385e-16, Final residual = 1.09385e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.22949e-16, Final residual = 1.22949e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30525e-08
ExecutionTime = 4.98 s ClockTime = 9 s

Time = 989

DILUPBiCG: Solving for Ux, Initial residual = 1.23595e-16, Final residual = 1.23595e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.15446e-16, Final residual = 1.15446e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.21323e-16, Final residual = 1.21323e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30534e-08
ExecutionTime = 4.98 s ClockTime = 9 s

Time = 990

DILUPBiCG: Solving for Ux, Initial residual = 1.26196e-16, Final residual = 1.26196e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.08924e-16, Final residual = 1.08924e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.23746e-16, Final residual = 1.23746e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30542e-08
ExecutionTime = 4.98 s ClockTime = 9 s

Time = 991

DILUPBiCG: Solving for Ux, Initial residual = 1.23788e-16, Final residual = 1.23788e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.12266e-16, Final residual = 1.12266e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.22859e-16, Final residual = 1.22859e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30551e-08
ExecutionTime = 4.98 s ClockTime = 9 s

Time = 992

DILUPBiCG: Solving for Ux, Initial residual = 1.26728e-16, Final residual = 1.26728e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.1293e-16, Final residual = 1.1293e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.21393e-16, Final residual = 1.21393e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30559e-08
ExecutionTime = 4.99 s ClockTime = 9 s

Time = 993

DILUPBiCG: Solving for Ux, Initial residual = 1.23065e-16, Final residual = 1.23065e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.11725e-16, Final residual = 1.11725e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.23649e-16, Final residual = 1.23649e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30568e-08
ExecutionTime = 5 s ClockTime = 9 s

Time = 994

DILUPBiCG: Solving for Ux, Initial residual = 1.26933e-16, Final residual = 1.26933e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.09154e-16, Final residual = 1.09154e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.22979e-16, Final residual = 1.22979e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30576e-08
ExecutionTime = 5 s ClockTime = 9 s

Time = 995

DILUPBiCG: Solving for Ux, Initial residual = 1.23577e-16, Final residual = 1.23577e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.15583e-16, Final residual = 1.15583e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.21322e-16, Final residual = 1.21322e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30585e-08
ExecutionTime = 5.01 s ClockTime = 9 s

Time = 996

DILUPBiCG: Solving for Ux, Initial residual = 1.26195e-16, Final residual = 1.26195e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.09024e-16, Final residual = 1.09024e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.2373e-16, Final residual = 1.2373e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30593e-08
ExecutionTime = 5.02 s ClockTime = 9 s

Time = 997

DILUPBiCG: Solving for Ux, Initial residual = 1.23799e-16, Final residual = 1.23799e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.12231e-16, Final residual = 1.12231e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.22866e-16, Final residual = 1.22866e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30602e-08
ExecutionTime = 5.02 s ClockTime = 9 s

Time = 998

DILUPBiCG: Solving for Ux, Initial residual = 1.2673e-16, Final residual = 1.2673e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.12967e-16, Final residual = 1.12967e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.21424e-16, Final residual = 1.21424e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.3061e-08
ExecutionTime = 5.03 s ClockTime = 9 s

Time = 999

DILUPBiCG: Solving for Ux, Initial residual = 1.23049e-16, Final residual = 1.23049e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.11804e-16, Final residual = 1.11804e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.2364e-16, Final residual = 1.2364e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30619e-08
ExecutionTime = 5.03 s ClockTime = 9 s

Time = 1000

DILUPBiCG: Solving for Ux, Initial residual = 1.26929e-16, Final residual = 1.26929e-16, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 1.09316e-16, Final residual = 1.09316e-16, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1.22938e-16, Final residual = 1.22938e-16, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.10497e-07, Final residual = 7.10497e-07, No Iterations 0
time step continuity errors : sum local = 3.29168e-12, global = -8.50298e-13, cumulative = -1.30627e-08
ExecutionTime = 5.05 s ClockTime = 10 s

End






I can't find the problem, the issue. Someone can help me?

Thank U!

MartinB April 12, 2011 07:14

Hi,

your simulation seems to be fully converged... how does it look like in Paraview?

Martin

Lord Kelvin April 12, 2011 07:19

Quote:

Originally Posted by MartinB (Post 303249)
Hi,

your simulation seems to be fully converged... how does it look like in Paraview?

Martin

Hi Martin, yes it "seems" but the results says "No Iterations 0" and the initial value and the final value for velocity and pressure are THE SAME.

I don't understand this issue. absolutely :(

MartinB April 12, 2011 07:27

If you decrease the tolerances for the linear equation solver in system/fvSolution even further to let's say "tolerance 1e-12;", then the initial residual is higher then desired and more iterations will be done...

But it shouldn't be necessary... your simulation results should be fine enough after a few hundred iterations.

You can add "convergence 1e-5;" to the SIMPLE dictionary in the fvSolution. simpleFoam will stop as soon as convergence criteria is reached:
Code:

SIMPLE
{
    nNonOrthogonalCorrectors 0;
    convergence 1.0e-5;
}

Martin

Lord Kelvin April 12, 2011 07:52

Quote:

Originally Posted by MartinB (Post 303254)
If you decrease the tolerances for the linear equation solver in system/fvSolution even further to let's say "tolerance 1e-12;", then the initial residual is higher then desired and more iterations will be done...

But it shouldn't be necessary... your simulation results should be fine enough after a few hundred iterations.

You can add "convergence 1e-5;" to the SIMPLE dictionary in the fvSolution. simpleFoam will stop as soon as convergence criteria is reached:
Code:

SIMPLE
{
    nNonOrthogonalCorrectors 0;
    convergence 1.0e-5;
}

Martin

Martin, you mean that my cylinder is too simple and banal and so the solver doesn't need to make iterations beacause the value (start-end) are quite the same??

so the problem is in the solid model?

MartinB April 12, 2011 07:58

If simpleFoam makes 0 iterations for solving the linear equations system in the very first time steps, too, than there is a problem in your case. On the other hand if simpleFoam do make more than 0 iterations in the first time steps, everything is fine: simpleFoam found the correct solution and further iterations are not necessary.

You can send me your case, if you like, so I can have a look at it... my eMail comes via boardmail to prevent spamming...

Martin

Lord Kelvin April 12, 2011 11:24

Quote:

Originally Posted by MartinB (Post 303262)
If simpleFoam makes 0 iterations for solving the linear equations system in the very first time steps, too, than there is a problem in your case. On the other hand if simpleFoam do make more than 0 iterations in the first time steps, everything is fine: simpleFoam found the correct solution and further iterations are not necessary.

You can send me your case, if you like, so I can have a look at it... my eMail comes via boardmail to prevent spamming...

Martin

I want to underline to the community the great availibility of Martin.

I want to give him REP+

:)


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