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soonic March 29, 2012 10:40

simpleFoam /water in pipes/ how to obtain and tune the solution?
 
4 Attachment(s)
Dont know how to hide or delete this for now, but i found mismatched BC. But maybe I will need help later. Thanks for visit.

Hello,

I am solving water flowing in pipe in steadyState by simpleFoam. I have Re~20000. Velocities 12m/s. I am unable to converge with my case. I did a comparison of case with laminar vs. k-eps regime, and tetra vs. polyhedral mesh (produced by polyDualMesh from that tets). Could you help me to tune up fvSchemes and fv Solution, please ? Or is it grid or BC related issue ?


I have read and tried several ideas written on the forum but no big success. I also divided the case in solving bended knee only, T-juction only. They have converged, but now the solution blows up e.g. on k and epsilon bounding and time step continuity error at some point of computation. I would like to compute temperature fields later on, but I am unable to solve flow for now.

my case:
http://soonic.cesnak.org/cfd/pipe.png

boundaries are like: green inlet (hot water); red outlet (hot water); red inlet(cold water); blue outlet(cold water). Hot outlet and cold inlet is the same diameter and mass flow.
Files from system folder are attached. CheckMesh for both meshes as well. BCs are in the end of post. Now I will show resiaduals. Maybe somebody knows what happens there.

Thank you


http://soonic.cesnak.org/cfd/lam_pol..._thumbnail.png
http://soonic.cesnak.org/cfd/lam_pol...b_polyTurb.png




p
Code:

internalField  uniform 0;

boundaryField
{
    inh
    {
        type            zeroGradient;
    }
    inc
    {
        type            zeroGradient;
    }   
    outh
    {
    type            fixedValue;
        value          uniform 0;
    }
    outc
    {
        type            zeroGradient;
    }
    stena
    {
        type            zeroGradient;
    }

U
Code:

internalField  uniform (0 0 0 );

boundaryField
{
    inh
    {
        type            fixedValue;
        value          uniform (0.504 0 0); //Value is half scaled for laminar case
    }
    outh
    {
        type            fixedValue;
        value          uniform (0 1.7654 0); //Value is half scaled for laminar case
    }
    inc
    {
        type            fixedValue;
        value          uniform (0 -1.7654 0); //Value is half scaled for laminar case
    }
    outc
    {
        type            zeroGradient;
    }
    stena
    {
        type            fixedValue;
        value          uniform (0 0 0);
    }
}

k
Code:

internalField  uniform 0.004;

boundaryField
{
    inh
    {
        type            turbulentIntensityKineticEnergyInlet;
        intensity      0.04726;
        U              U;
        phi            phi;
        value          uniform 0.000852;
    }
    outh
    {
        type            turbulentIntensityKineticEnergyInlet;
        intensity      0.04229;
        U              U;
        phi            phi;
        value          uniform 0.00836;
    }
    inc
    {
        type            turbulentIntensityKineticEnergyInlet;
        intensity      0.04229;
        U              U;
        phi            phi;
        value          uniform 0.00836;
    }
    outc
    {
        type            zeroGradient;
    }
    stena
    {
        type            kqRWallFunction;
        value          uniform 0.001;
    }

epsilon
Code:

internalField  uniform 100;

boundaryField
{
    inh
    {
        type            turbulentMixingLengthDissipationRateInlet;
        mixingLength    0.034678;
        phi            phi;
        k              k;
        value          uniform 0.0001179;
    }
    outh
    {
        type            turbulentMixingLengthDissipationRateInlet;
        mixingLength    0.02407;
        phi            phi;
        k              k;
        value          uniform 0.0052217;
    }
    inc
    {
        type            turbulentMixingLengthDissipationRateInlet;
        mixingLength    0.02407;
        phi            phi;
        k              k;
        value          uniform 0.0052217;
    }
    outc
    {
        type            zeroGradient;
    }
    stena
    {
        type            epsilonWallFunction;
        value          uniform 0.001;
    }
}



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