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Sudden stop of heating - convergence problem?

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Old   February 2, 2021, 04:34
Default Sudden stop of heating - convergence problem?
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I simulate with OF8, chtMultiRegionFoam and Euler heating of a solid block, inside are two pipes filled with a fluid (water, velocity=0), every region has the same temperature.

The upper surface heats up the block and my goal is to know how much time does it need to heat up the whole block.

Unfortunately, after around 400.000 seconds the heating stops suddenly. The program does not crash, but in the next houndred thousand of seconds is almost no heating happening, which is implausible.

I expected wrong settings in fvSolution, so I tried different:
number of iterations (1-50),
relaxation Factors between 0.1 - 1,
nNonOrthogonalCorrectors from 0-2,
outerCorrectorResidualControl switched on and off.

all with the same outcome: at a certain temperature reached, the heating stops suddenly and almost completly.

Are there any settings influencing my problem, I could have forgotten or adjusted wrong?
Thank you in advance for your help!


Code:
/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  6
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
    default         Euler; // Euler steadyState
}

gradSchemes
{
    default         Gauss linear;
}

divSchemes
{
    default         none;
}

laplacianSchemes
{
    default             none;
    laplacian(alpha,e)  Gauss linear uncorrected;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         uncorrected;
}


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

Code:
/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  6
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
    e
    {
        solver           PCG;
        preconditioner   DIC;
        tolerance        1e-06;
        relTol           0.1;
    }

    eFinal
    {
        $e;
        tolerance        1e-06;
        relTol           0;
    }

}

PIMPLE
{
    nNonOrthogonalCorrectors 0;
    outerCorrectorResidualControl
    {
        e
        {
            tolerance 1e-7;//5
            relTol 0;
        }
    }
}

relaxationFactors
{
    equations
    {
        e           0.1;

    }
}

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


Code:
/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  8
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

application     chtMultiRegionFoam;

startFrom       latestTime;

startTime       0;

stopAt          endTime;

endTime         864000;

deltaT          1;

writeControl    adjustableRunTime;

writeInterval   3600;

purgeWrite      0;

writeFormat     ascii;

writePrecision  22;

writeCompression off;

timeFormat      general;

timePrecision   6;

runTimeModifiable true;

adjustTimeStep  true; 

maxCo           1;

functions
{

  #includeFunc "residuals_fluid"

  avT_fluid_outlet
  {
      type            surfaceFieldValue;
      libs            ("libfieldFunctionObjects.so");
      log             yes;
      writeControl    runTime;
      writeInterval   3600;	
      writeFields     false;
      surfaceFormat   none;
      regionType      patch;
      name            outlet;
      region 	      fluid;	
      operation       areaAverage;
      fields
      (
          T
      );
  }

  yPlus_fluid
  {
    type            yPlus;
    libs            ("libfieldFunctionObjects.so");
    executeControl  writeTime;
    writeControl    writeTime;
    region  fluid;
  } 

  wallHeatFlux_fluid
  {
    type            wallHeatFlux;
    libs            ("libfieldFunctionObjects.so");
    executeControl  writeTime;
    writeControl    writeTime;
    region  fluid;
  }

  wallShearStress_fluid
  {
    type            wallShearStress;
    libs            ("libfieldFunctionObjects.so");
    executeControl  writeTime;
    writeControl    writeTime;
    region  fluid;
  }

  turbulenceIntensity_fluid
  {
    type            turbulenceIntensity;
    libs            ("libfieldFunctionObjects.so");
    executeControl  writeTime;
    writeControl    writeTime;
    region  fluid;
  } 

}


libs (
"libOpenFOAM.so"
"libsimpleSwakFunctionObjects.so"
"libswakFunctionObjects.so"
"libgroovyBC.so"
);

// ************************************************************************* //
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File Type: jpg average_temp_euler.JPG (19.5 KB, 3 views)
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chtmulitregionfoam, convergance, euler

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