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Problem with chtMultiregionFoam radiation boundary condition

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Old   August 19, 2015, 06:48
Thumbs down Problem with chtMultiregionFoam radiation boundary condition
  #1
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baran
Join Date: Aug 2014
Posts: 45
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Greeting all!!!

I have a simple case as follows...in OF 2.4
1. Cavity with heater inside
2. Surrounding this cavity some insulation is there

So I run the radiation case(with view factor model) in chtMultiregionFoam(transient) with interface boundary condition of solid and air..
Code:
type            compressible::turbulentTemperatureCoupledBaffleMixed;
        value           uniform 300;
        Tnbr            T;
        kappa           fluidThermo;
        kappaName       none;
Fluid thermo property is tutorial one. It is run completely okay and I run it for around 360 sec then stop that one.Log file after 360 sec is like this...

Code:
Region: fluid Courant Number mean: 0.009927002 max: 0.29967996
Region: fibrothal_in Diffusion Number mean: 5.0662336e-08 max: 3.0645162e-07
Region: solid_bricks Diffusion Number mean: 3.3063735e-08 max: 1.7757998e-07
Region: unifrax_out Diffusion Number mean: 1.0011137e-07 max: 3.0843423e-07
deltaT = 0.0010946195
Time = 356.6388


Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 0.00025637481, Final residual = 4.407068e-09, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.00027934907, Final residual = 9.510753e-09, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.0002301347, Final residual = 1.7324477e-09, No Iterations 2
DILUPBiCG:  Solving for h, Initial residual = 3.1476392e-05, Final residual = 7.3471181e-08, No Iterations 1
Min/max T:313.58391 1118
GAMG:  Solving for p_rgh, Initial residual = 8.5854497e-05, Final residual = 9.4845113e-08, No Iterations 7
GAMG:  Solving for p_rgh, Initial residual = 3.5173418e-06, Final residual = 5.4325282e-08, No Iterations 3
GAMG:  Solving for p_rgh, Initial residual = 8.6238562e-07, Final residual = 3.8513529e-08, No Iterations 2
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 6.074565e-10, global = 6.3652211e-13, cumulative = -2.197283e-07
GAMG:  Solving for p_rgh, Initial residual = 1.0315776e-06, Final residual = 3.9160376e-08, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 1.669925e-07, Final residual = 2.9482081e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 6.8532497e-08, Final residual = 6.8532497e-08, No Iterations 0
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 1.080931e-09, global = -4.0250703e-14, cumulative = -2.1972834e-07

Solving for solid region fibrothal_in
DICPCG:  Solving for h, Initial residual = 1.2940158e-06, Final residual = 1.3251284e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.7071703e-12, Final residual = 1.7071703e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 640.55258

Solving for solid region solid_bricks
DICPCG:  Solving for h, Initial residual = 1.0267441e-06, Final residual = 4.8127074e-13, No Iterations 1
DICPCG:  Solving for h, Initial residual = 8.4350547e-13, Final residual = 8.4350547e-13, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 458.84315

Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 9.9373252e-07, Final residual = 9.9373252e-07, No Iterations 0
DICPCG:  Solving for h, Initial residual = 9.9373252e-07, Final residual = 9.9373252e-07, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 303.89972
ExecutionTime = 133423.49 s  ClockTime = 136999 s

Region: fluid Courant Number mean: 0.0099269187 max: 0.29966461
Region: fibrothal_in Diffusion Number mean: 5.0662347e-08 max: 3.0645172e-07
Region: solid_bricks Diffusion Number mean: 3.3063735e-08 max: 1.7757998e-07
Region: unifrax_out Diffusion Number mean: 1.0011137e-07 max: 3.0843423e-07
deltaT = 0.0010946195
Time = 356.6399


Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 0.00025636135, Final residual = 4.3780302e-09, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.00027935499, Final residual = 1.0088861e-08, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.00023013524, Final residual = 1.6871542e-09, No Iterations 2
DILUPBiCG:  Solving for h, Initial residual = 3.1473979e-05, Final residual = 7.3570805e-08, No Iterations 1
Min/max T:313.58441 1118
GAMG:  Solving for p_rgh, Initial residual = 8.5834205e-05, Final residual = 9.5254497e-08, No Iterations 7
GAMG:  Solving for p_rgh, Initial residual = 3.5163029e-06, Final residual = 5.4570072e-08, No Iterations 3
GAMG:  Solving for p_rgh, Initial residual = 8.6202952e-07, Final residual = 3.8610652e-08, No Iterations 2
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 6.0899296e-10, global = 6.481879e-13, cumulative = -2.1972769e-07
GAMG:  Solving for p_rgh, Initial residual = 1.0315463e-06, Final residual = 3.9050125e-08, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 1.6693103e-07, Final residual = 2.9416253e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 6.8558156e-08, Final residual = 6.8558156e-08, No Iterations 0
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 1.081336e-09, global = -3.652917e-14, cumulative = -2.1972773e-07

Solving for solid region fibrothal_in
DICPCG:  Solving for h, Initial residual = 1.2940145e-06, Final residual = 1.3250951e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.7071583e-12, Final residual = 1.7071583e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 640.55404

Solving for solid region solid_bricks
DICPCG:  Solving for h, Initial residual = 1.0267414e-06, Final residual = 4.812706e-13, No Iterations 1
DICPCG:  Solving for h, Initial residual = 8.4350791e-13, Final residual = 8.4350791e-13, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 458.84273

Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 9.9373296e-07, Final residual = 9.9373296e-07, No Iterations 0
DICPCG:  Solving for h, Initial residual = 9.9373296e-07, Final residual = 9.9373296e-07, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 303.89975
ExecutionTime = 133424 s  ClockTime = 137000 s
Then i changed the boundary condition of fluid and solid interface ..
Code:
   type            	compressible::turbulentTemperatureRadCoupledMixed;
        value           uniform 300;
        Tnbr            T;
        kappa               fluidThermo;
        QrNbr           none;
        Qr              Qr;
        kappaName           none;
fvSolution of air is as follows...
Code:
solvers
{
    rho
    {
        solver          PCG;
        preconditioner  DIC;
        tolerance       1e-7;
        relTol          0;
    }

    rhoFinal
    {
        $rho;
        tolerance       1e-7;
        relTol          0;
    }

    p_rgh
    {
        solver           GAMG;
        tolerance        1e-7;
        relTol           0;

        smoother         GaussSeidel;

        cacheAgglomeration  true;
        nCellsInCoarsestLevel 10;
        agglomerator     faceAreaPair;
        mergeLevels      1;
    }

    p_rghFinal
    {
        $p_rgh;
        tolerance        1e-7;
        relTol           0;
    }

    "(U|h|k|omega|epsilon|R)"
    {
        solver           PBiCG;
        preconditioner   DILU;
        tolerance        1e-7;
        relTol           0.1;
    }

    "(U|h|k|omega|epsilon|R)Final"
    {
        $U;
        tolerance        1e-7;
        relTol           0;
    }


}

PIMPLE
{
    momentumPredictor   on;
    nCorrectors         2;
    nNonOrthogonalCorrectors 2;
}


relaxationFactors
{
    fields
    {
        rho             0.1;
        p_rgh           0.1;

    }
    equations
    {
        "h.*"           0.1;
        "U.*"           0.1;
        "(k|epsilon|R)" 0.1;
        G               0.1;
        "ILambda.*"     0.1;
        Qr              0.1;


    }

}
fvScheme of air air is as follows...
Code:
ddtSchemes
{
    default         Euler;
}

gradSchemes
{
    default         cellLimited Gauss linear 1;     //    Gauss linear;
}

divSchemes
{
    default         none;
    div(phi,U)       Gauss upwind;
    div(phi,k)       Gauss upwind;
    div(phi,K)       Gauss linear;   // Gauss upwind;
    div(phi,epsilon) Gauss upwind;
    div(phi,h)       Gauss upwind;
    div(phi,omega)   Gauss upwind;
    div(phi,R)       Gauss upwind;
    div(R)          Gauss linear;
    div(Ji,Ii_h)    Gauss linearUpwind grad(U);
    div((muEff*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
    default         none;
    laplacian(rhorAUf,p_rgh) Gauss linear limited 0.333;
    laplacian(muEff,U) Gauss linear limited 0.333;
    laplacian((rho*(1|A(U))),p_rgh) Gauss linear limited 0.333;
    laplacian(alphaEff,h) Gauss linear limited 0.333;
    laplacian(DepsilonEff,epsilon) Gauss linear limited 0.333;
    laplacian(DkEff,k) Gauss linear limited 0.333;
    laplacian(DomegaEff,omega) Gauss linear limited 0.333;
    laplacian(DREff,R) Gauss linear limited 0.333;
    laplacian(gammaRad,G) Gauss linear limited 0.333;

}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default        limited 0.333;
}

fluxRequired
{
    default         no;
    p_rgh;
}
Initially it is running well but after some iteration it is giving negative value of T in fluid zone ,then it is diverged.....showing
Code:
Maximum numbers of iterations exceeded
It is giving in practical results.....
Apart from this bc remaining thing is same for two cases...Is there is a problem with this boundary condition..??
Please suggest something...
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Old   August 20, 2015, 09:01
Default
  #2
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Alex
Join Date: Oct 2013
Posts: 337
Rep Power: 17
zfaraday will become famous soon enough
Hi baran,

You did good in providing as much information as you could. However, maybe more information might be needed in order to figure out what is going wrong in your case. For instance, you should upload the log file of the run that crashed in order to be able to start guessing things... For how long has it been runing?

In the last cases I run where radaitive heat transfer was taken into account I found out that the balance on patches was somewhat critical in the first time steps. It was due to the sudden variation of the gradients at patches when radiation was computed. However, I never faced this problem with the turbulentTemperatureRadCoupledMixed patch type, but I had some similar issue with thermalBaffle1D and externalWallHeatFluxTemperature instead. The solution to avoid getting a crashed run was to implement a relaxation factor method to prevent the already mentioned problem of gradient variation. You should take a look into the code of these BC's in order to understand what I am talking about, maybe something like that may be usefull. Nevertheless, I recall that I never had this problem with the turbulentTemperatureRadCoupledMixed patch type... Have you used any of the other mentioned patch types in your simulation?

Another advice I give you is that you should try to visualize with paraview the thermal distribution in the last time step before the run crashed. By doing that you could be able to find out what cells are causing the trouble. After that you can start guessing what is going wrong with more accuracy.

I hope my advices will come in handy to you.

Best regards,

Alex

_______________________
Quick update: I worked with chtMultiRegionSimpleFoam solver and radiation was solved with fvDOM method in my case.
__________________
Web site where I present my Master's Thesis: foamingtime.wordpress.com

The case I talk about in this site was solved with chtMultiRegionSimpleFoam solver and involves radiation. Some basic tutorials are also resolved step by step in the web. If you are interested in these matters, you are invited to come in!

Last edited by zfaraday; August 20, 2015 at 09:03. Reason: Quick update added
zfaraday is offline   Reply With Quote

Old   August 20, 2015, 10:29
Default
  #3
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baran
Join Date: Aug 2014
Posts: 45
Rep Power: 7
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This is the log file of that case....from where it is started diverging...
Quote:
Region: fibrothal_in Diffusion Number mean: 3.7268416e-08 max: 2.2962241e-07
Region: solid_bricks Diffusion Number mean: 2.512897e-08 max: 1.3494945e-07
Region: unifrax_out Diffusion Number mean: 7.6077766e-08 max: 2.3438883e-07
deltaT = 0.00083183564
Time = 73.539995


Solving for fluid region fluid
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Ux, Initial residual = 6.7636734e-05, Final residual = 1.3441408e-08, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 4.6392292e-05, Final residual = 1.0721153e-08, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 6.0782809e-05, Final residual = 8.146975e-09, No Iterations 1
DILUPBiCG: Solving for h, Initial residual = 1.4442565e-05, Final residual = 1.5485771e-09, No Iterations 1
Min/max T:302.35042 796
GAMG: Solving for p_rgh, Initial residual = 0.0056481889, Final residual = 8.1606344e-08, No Iterations 7
GAMG: Solving for p_rgh, Initial residual = 4.0515088e-06, Final residual = 4.6215754e-08, No Iterations 3
GAMG: Solving for p_rgh, Initial residual = 9.1679808e-07, Final residual = 3.0994507e-08, No Iterations 2
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 1.4519277e-11, global = 7.237251e-13, cumulative = 4.4382842e-08
GAMG: Solving for p_rgh, Initial residual = 3.9095027e-07, Final residual = 4.9657638e-08, No Iterations 1
GAMG: Solving for p_rgh, Initial residual = 1.3685112e-07, Final residual = 2.4273418e-08, No Iterations 1
GAMG: Solving for p_rgh, Initial residual = 5.9664268e-08, Final residual = 5.9664268e-08, No Iterations 0
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 2.7949542e-11, global = 4.6906331e-13, cumulative = 4.4383311e-08

Solving for solid region fibrothal_in
DICPCG: Solving for h, Initial residual = 7.0222902e-06, Final residual = 4.4745359e-12, No Iterations 1
DICPCG: Solving for h, Initial residual = 4.8146941e-12, Final residual = 4.8146941e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 654.37783

Solving for solid region solid_bricks
DICPCG: Solving for h, Initial residual = 5.3096873e-06, Final residual = 1.9608229e-12, No Iterations 1
DICPCG: Solving for h, Initial residual = 3.6329413e-12, Final residual = 3.6329413e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 691.02751

Solving for solid region unifrax_out
DICPCG: Solving for h, Initial residual = 3.415013e-06, Final residual = 3.0740924e-12, No Iterations 1
DICPCG: Solving for h, Initial residual = 3.1231553e-12, Final residual = 3.1231553e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 302.19046
ExecutionTime = 25647.98 s ClockTime = 26270 s

Region: fluid Courant Number mean: 0.01846859 max: 0.29994596
Region: fibrothal_in Diffusion Number mean: 3.7268432e-08 max: 2.2962282e-07
Region: solid_bricks Diffusion Number mean: 2.5128969e-08 max: 1.3494945e-07
Region: unifrax_out Diffusion Number mean: 7.6077766e-08 max: 2.3438883e-07
deltaT = 0.00083183564
Time = 73.540827
Solving for fluid region fluid
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Ux, Initial residual = 6.7630737e-05, Final residual = 1.3418181e-08, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 4.6370261e-05, Final residual = 1.0742627e-08, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 6.0847475e-05, Final residual = 8.1523053e-09, No Iterations 1
DILUPBiCG: Solving for h, Initial residual = 1.4442106e-05, Final residual = 1.5490886e-09, No Iterations 1

LU Back substitute C matrix..
Min/max T:302.35057 796
GAMG: Solving for p_rgh, Initial residual = 0.0056481019, Final residual = 7.6797676e-08, No Iterations 7
GAMG: Solving for p_rgh, Initial residual = 3.857246e-06, Final residual = 9.7154467e-08, No Iterations 2
GAMG: Solving for p_rgh, Initial residual = 8.8653178e-07, Final residual = 3.3270662e-08, No Iterations 2
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 1.5585688e-11, global = -4.472e-13, cumulative = 4.4382864e-08
GAMG: Solving for p_rgh, Initial residual = 3.7940167e-07, Final residual = 4.9666952e-08, No Iterations 1
GAMG: Solving for p_rgh, Initial residual = 1.3330598e-07, Final residual = 2.477867e-08, No Iterations 1
GAMG: Solving for p_rgh, Initial residual = 5.9175294e-08, Final residual = 5.9175294e-08, No Iterations 0
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 2.7720599e-11, global = -2.3320649e-13, cumulative = 4.4382631e-08

Solving for solid region fibrothal_in
DICPCG: Solving for h, Initial residual = 7.0243905e-06, Final residual = 4.4725576e-12, No Iterations 1
DICPCG: Solving for h, Initial residual = 2.4377613e-11, Final residual = 2.4377613e-11, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 654.37063

Solving for solid region solid_bricks
DICPCG: Solving for h, Initial residual = 5.2875841e-06, Final residual = 1.9709967e-12, No Iterations 1
DICPCG: Solving for h, Initial residual = 2.8414773e-09, Final residual = 2.8414773e-09, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 295.48786 max(T) [0 0 0 1 0 0 0] 741.78106

Solving for solid region unifrax_out
DICPCG: Solving for h, Initial residual = 3.4149741e-06, Final residual = 3.0740581e-12, No Iterations 1
DICPCG: Solving for h, Initial residual = 3.1189356e-12, Final residual = 3.1189356e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 302.19047
ExecutionTime = 25648.68 s ClockTime = 26271 s

Region: fluid Courant Number mean: 0.018468399 max: 0.29995557
Region: fibrothal_in Diffusion Number mean: 3.7268448e-08 max: 2.2962323e-07
Region: solid_bricks Diffusion Number mean: 2.5128969e-08 max: 1.3494945e-07
Region: unifrax_out Diffusion Number mean: 7.6077766e-08 max: 2.3438883e-07
deltaT = 0.00083183564
Time = 73.541659


Solving for fluid region fluid
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Ux, Initial residual = 6.7625913e-05, Final residual = 1.3402331e-08, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 4.6344566e-05, Final residual = 1.0754375e-08, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 6.0932861e-05, Final residual = 8.1687571e-09, No Iterations 1
DILUPBiCG: Solving for h, Initial residual = 1.4447945e-05, Final residual = 1.5504852e-09, No Iterations 1
Min/max T:292.46006 796
GAMG: Solving for p_rgh, Initial residual = 0.0056581752, Final residual = 7.6764428e-08, No Iterations 12
GAMG: Solving for p_rgh, Initial residual = 2.2938121e-05, Final residual = 5.568475e-08, No Iterations 5
GAMG: Solving for p_rgh, Initial residual = 4.8180826e-06, Final residual = 4.5585251e-08, No Iterations 3
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 2.1354346e-11, global = -1.0446098e-12, cumulative = 4.4381586e-08
GAMG: Solving for p_rgh, Initial residual = 1.7763567e-06, Final residual = 4.7846782e-08, No Iterations 2
GAMG: Solving for p_rgh, Initial residual = 5.9132237e-07, Final residual = 5.9130769e-08, No Iterations 1
GAMG: Solving for p_rgh, Initial residual = 2.4540226e-07, Final residual = 3.1298447e-08, No Iterations 1
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 1.4662065e-11, global = -6.7971007e-14, cumulative = 4.4381518e-08

Solving for solid region fibrothal_in
DICPCG: Solving for h, Initial residual = 7.0245586e-06, Final residual = 4.4724421e-12, No Iterations 1
DICPCG: Solving for h, Initial residual = 9.1267502e-12, Final residual = 9.1267502e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 654.37584

Solving for solid region solid_bricks
DICPCG: Solving for h, Initial residual = 5.2888596e-06, Final residual = 1.9709382e-12, No Iterations 1
DICPCG: Solving for h, Initial residual = 8.289224e-11, Final residual = 8.289224e-11, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 292.46034 max(T) [0 0 0 1 0 0 0] 661.85799

Solving for solid region unifrax_out
DICPCG: Solving for h, Initial residual = 3.4149352e-06, Final residual = 3.0740239e-12, No Iterations 1
DICPCG: Solving for h, Initial residual = 3.127232e-12, Final residual = 3.127232e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 302.19048
ExecutionTime = 25649.12 s ClockTime = 26271 s

Region: fluid Courant Number mean: 0.018468212 max: 0.29996512
Region: fibrothal_in Diffusion Number mean: 3.7268464e-08 max: 2.2962363e-07
Region: solid_bricks Diffusion Number mean: 2.5128969e-08 max: 1.3494945e-07
Region: unifrax_out Diffusion Number mean: 7.6077766e-08 max: 2.3438883e-07
deltaT = 0.00083183564
Time = 73.54249


Solving for fluid region fluid
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Ux, Initial residual = 6.7947711e-05, Final residual = 1.4502077e-08, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 4.6627109e-05, Final residual = 1.1456384e-08, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 6.1359507e-05, Final residual = 7.2212648e-09, No Iterations 1
DILUPBiCG: Solving for h, Initial residual = 1.4447972e-05, Final residual = 1.5510617e-09, No Iterations 1
Min/max T:292.4726 796
GAMG: Solving for p_rgh, Initial residual = 0.0056490789, Final residual = 8.349077e-08, No Iterations 10
GAMG: Solving for p_rgh, Initial residual = 1.4609603e-05, Final residual = 6.3234719e-08, No Iterations 4
GAMG: Solving for p_rgh, Initial residual = 3.3731476e-06, Final residual = 8.6407996e-08, No Iterations 2
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 4.0477576e-11, global = 2.3788157e-14, cumulative = 4.4381542e-08
GAMG: Solving for p_rgh, Initial residual = 1.3010508e-06, Final residual = 4.1176202e-08, No Iterations 2

Last edited by baran_foam; August 20, 2015 at 10:30. Reason: modify
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Old   August 20, 2015, 15:30
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Greetings to all!

@baran_foam: Since you sent me a PM and I spent some time trying to imagine/diagnose this issue, my best guess is that there is no heat being released by the region "solid_bricks", which is why it ends up overheating and crashing the simulation, because the temperature range falls out of the working range of the polynomials for the material properties.

Beyond that, you should follow Alex's suggestion, specially the one about looking at the results in ParaView.

Best regards,
Bruno
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Old   August 24, 2015, 02:17
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Greeting All!!!
@bruno ....thanks for your reply....and I will check that issue...
@Alex... thanks for your valuable suggestion...
1. for bc in heating element surface I have used uniformFixedValue
2. for outer wall I have used

Code:
        type            externalWallHeatFluxTemperature;
        kappa               solidThermo;
        Ta              uniform 303;
        h               uniform 10;
        kappaName           none;
        value           uniform 300;
...the same thing I have used for my previous case also...
can you kindly explain what kind of problem you faced with externalWallHeatFluxTemperature bc?

I have to check other things as you told and let you know wheather any other issue is there or not...

Regards,
Baran
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Old   August 24, 2015, 09:54
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Hi baran,

You can check youself the problem I faced here. What OF version are you using? If you use 2.3.x or 2.4.x you can fix it by downloading the fixes via github and recompile it. The fix consists of a relaxation factor implemented for the Qr field so that you only need to specify a couple of fields more in the BC specification. By the way, in the BC specification you attached you din't have Qr defined and you need to define it in order to take radiation into account in the boundaries...

Hope it helps!

Alex
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The case I talk about in this site was solved with chtMultiRegionSimpleFoam solver and involves radiation. Some basic tutorials are also resolved step by step in the web. If you are interested in these matters, you are invited to come in!
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Old   August 26, 2015, 08:21
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Dear Alex,

my OF version is 2.4.x
This same case I have run in fluent to compare the two result . As thermal conductivity is very low of this solid zone. Wheather I add radiation at the outer wall does not have any effect.

Thermal conductivity of bricks is 0.15 .
I want to ask another question..that..if I am applying viewfactor model but wall bc is like convection case then viewfactor effect is come into consideration?

Regards,
baran
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Old   August 31, 2015, 07:02
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Greeting all!!!

This is mesh quality of my geometry...I hope this is not made any problem...

Code:
Create polyMesh for time = 0

Enabling all (cell, face, edge, point) topology checks.

Enabling all geometry checks.

Time = 0

Mesh stats
    points:           1116300
    faces:            3270406
    internal faces:   3191462
    cells:            1076978
    faces per cell:   6
    boundary patches: 10
    point zones:      0
    face zones:       13
    cell zones:       4

Overall number of cells of each type:
    hexahedra:     1076978
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    0
    polyhedra:     0

Checking topology...
    Boundary definition OK.
    Cell to face addressing OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
    Topological cell zip-up check OK.
    Face-face connectivity OK.
    Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces...
    Patch               Faces    Points   Surface topology                   Bounding box
    he_surface          13720    13736    ok (closed singly connected)       (0.247 0.251 0.272) (0.917 0.941 1.202)
    w_right_side_ref    5952     6111     ok (non-closed singly connected)   (2.6999174e-24 0.15 0.212) (5.2351103e-16 1.036 1.352)
    w_left_side_ref     5952     6111     ok (non-closed singly connected)   (1.164 0.15 0.212) (1.164 1.036 1.352)
    w_back_ref          12288    12513    ok (non-closed singly connected)   (0 0.15 1.352) (1.164 1.036 1.502)
    w_brick_bot         3256     3500     ok (non-closed singly connected)   (0.217 -9.5154073e-16 0.212) (0.947 9.5707519e-16 1.352)
    w_bot_ref           7104     7499     ok (non-closed singly connected)   (0 -1.1571817e-15 0.212) (1.164 0.15 1.502)
    w_door1             2588     2676     ok (non-closed singly connected)   (0.332 0.356 -0.1) (0.832 0.85600003 -0.05)
    w_door2             696      870      ok (non-closed singly connected)   (0.332 0.356 -0.05) (0.832 0.85600003 0)
    w_bricks            17028    17343    ok (non-closed singly connected)   (0 -1.1571817e-15 0) (1.164 1.186 0.212)
    w_top_ref           10360    10553    ok (non-closed singly connected)   (0 1.036 0.212) (1.164 1.186 1.502)

Checking geometry...
    Overall domain bounding box (0 -1.1571817e-15 -0.1) (1.164 1.186 1.502)
    Mesh (non-empty, non-wedge) directions (1 1 1)
    Mesh (non-empty) directions (1 1 1)
    Boundary openness (3.2928793e-15 2.2620737e-15 7.0567305e-15) OK.
    Max cell openness = 3.3154974e-16 OK.
    Max aspect ratio = 13.162501 OK.
    Minimum face area = 6.5776377e-06. Maximum face area = 0.00064648215.  Face area magnitudes OK.
    Min volume = 8.3282847e-08. Max volume = 7.9145335e-06.  Total volume = 2.0928022.  Cell volumes OK.
    Mesh non-orthogonality Max: 69.14912 average: 8.4597446
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 0.66268921 OK.
    Coupled point location match (average 0) OK.
    Face tets OK.
    Min/max edge length = 0.0016666666 0.032313618 OK.
    All angles in faces OK.
    Face flatness (1 = flat, 0 = butterfly) : min = 0.99388226  average = 0.99999605
    All face flatness OK.
    Cell determinant (wellposedness) : minimum: 0.028461416 average: 4.6877314
    Cell determinant check OK.
    Concave cell check OK.
    Face interpolation weight : minimum: 0.10005566 average: 0.49007212
    Face interpolation weight check OK.
    Face volume ratio : minimum: 0.11131699 average: 0.9662018
    Face volume ratio check OK.

Mesh OK.
Using the convection bc I have get my solution right though using radiation bc case is diverging as I told in my first place..Apart from this temperature variation with time is coming random with radiation bc....I have attached two point is air for this two case.. in picture(in total four...)

Can you suggest what might be the reason??


From the discussion of our previous case it is observed that case is diverging for radiation case...in bricks zone(thermal conductivity-0.15 J/kg K)
So I change the thermal conductivity of bricks from 0.15 to 10. Then run the same case with radiation bc....
Then case is diverging in other zone..fibrothal(thermal conductivity is around 0.15 J/kg K)...So is there is any problem with this radiation bc or radiation to handle high T with small thermal conductivity of insulation..


Please suggest something...mostly this problem is not involve with any mesh issue...??? I have attached the log file for the later case below...


Code:
Region: fluid Courant Number mean: 0.0198761 max: 0.29878319
Region: fibrothal_in Diffusion Number mean: 5.3692836e-08 max: 3.868369e-07
Region: solid_bricks Diffusion Number mean: 2.453461e-06 max: 1.317393e-05
Region: unifrax_out Diffusion Number mean: 1.0442085e-07 max: 3.2171136e-07
deltaT = 0.0011417394
Time = 132.83673


Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 7.8428474e-05, Final residual = 2.3160953e-08, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 5.9872307e-05, Final residual = 2.1848024e-08, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 8.1347697e-05, Final residual = 1.7257565e-08, No Iterations 1
DILUPBiCG:  Solving for h, Initial residual = 1.3754107e-05, Final residual = 1.8032295e-09, No Iterations 1
Min/max T:306.56532 939
GAMG:  Solving for p_rgh, Initial residual = 0.004153507, Final residual = 8.7413984e-08, No Iterations 10
GAMG:  Solving for p_rgh, Initial residual = 8.9189776e-06, Final residual = 8.0399224e-08, No Iterations 4
GAMG:  Solving for p_rgh, Initial residual = 2.1315608e-06, Final residual = 7.7674832e-08, No Iterations 2
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 6.4079763e-11, global = 8.4405831e-13, cumulative = 1.0816831e-07
GAMG:  Solving for p_rgh, Initial residual = 7.9826171e-07, Final residual = 3.8468735e-08, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 2.8369056e-07, Final residual = 4.4607049e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 1.209402e-07, Final residual = 2.6745305e-08, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 2.2064599e-11, global = 8.3155456e-15, cumulative = 1.0816832e-07

Solving for solid region fibrothal_in
DICPCG:  Solving for h, Initial residual = 4.8433956e-06, Final residual = 5.6555918e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 5.846885e-12, Final residual = 5.846885e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 823.55181

Solving for solid region solid_bricks
DICPCG:  Solving for h, Initial residual = 5.3780627e-06, Final residual = 1.8628724e-10, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.9739328e-10, Final residual = 1.9739328e-10, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300.00584 max(T) [0 0 0 1 0 0 0] 390.0248

Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 3.1120483e-06, Final residual = 3.4748384e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 3.5734963e-12, Final residual = 3.5734963e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 317.42316
ExecutionTime = 48515.92 s  ClockTime = 49698 s


Region: fluid Courant Number mean: 0.019876 max: 0.29877615
Region: fibrothal_in Diffusion Number mean: 5.3692908e-08 max: 3.8683897e-07
Region: solid_bricks Diffusion Number mean: 2.453461e-06 max: 1.317393e-05
Region: unifrax_out Diffusion Number mean: 1.0442085e-07 max: 3.2171136e-07
deltaT = 0.0011417394
Time = 132.83787


Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 7.8490734e-05, Final residual = 2.314818e-08, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 5.9735226e-05, Final residual = 2.1923582e-08, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 8.1540717e-05, Final residual = 1.7182041e-08, No Iterations 1
DILUPBiCG:  Solving for h, Initial residual = 1.3757046e-05, Final residual = 1.804325e-09, No Iterations 1

LU Back substitute C matrix..
Min/max T:306.56544 939
GAMG:  Solving for p_rgh, Initial residual = 0.0041498473, Final residual = 9.054912e-08, No Iterations 9
GAMG:  Solving for p_rgh, Initial residual = 8.3165628e-06, Final residual = 7.0594986e-08, No Iterations 4
GAMG:  Solving for p_rgh, Initial residual = 2.032543e-06, Final residual = 6.9336629e-08, No Iterations 2
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 5.7201248e-11, global = -9.3147623e-13, cumulative = 1.0816739e-07
GAMG:  Solving for p_rgh, Initial residual = 7.6577489e-07, Final residual = 9.7339006e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 2.8026848e-07, Final residual = 5.1413822e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 1.298081e-07, Final residual = 2.9943948e-08, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 2.4703296e-11, global = -6.8827074e-13, cumulative = 1.081667e-07

Solving for solid region fibrothal_in
DICPCG:  Solving for h, Initial residual = 4.8426671e-06, Final residual = 5.6623743e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 4.4247984e-11, Final residual = 4.4247984e-11, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 168.02419 max(T) [0 0 0 1 0 0 0] 823.54449

Solving for solid region solid_bricks
DICPCG:  Solving for h, Initial residual = 5.3882983e-06, Final residual = 1.8640842e-10, No Iterations 1
DICPCG:  Solving for h, Initial residual = 3.0063655e-10, Final residual = 3.0063655e-10, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300.00584 max(T) [0 0 0 1 0 0 0] 390.07683

Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 3.1120344e-06, Final residual = 3.4748206e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 3.5760929e-12, Final residual = 3.5760929e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 317.42353
ExecutionTime = 48516.76 s  ClockTime = 49698 s

Region: fluid Courant Number mean: 0.019875904 max: 0.29876907
Region: fibrothal_in Diffusion Number mean: 5.369298e-08 max: 3.8684106e-07
Region: solid_bricks Diffusion Number mean: 2.453461e-06 max: 1.317393e-05
Region: unifrax_out Diffusion Number mean: 1.0442085e-07 max: 3.2171136e-07
deltaT = 0.0011417394
Time = 132.83901

Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 7.8363917e-05, Final residual = 2.3111003e-08, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 5.9808245e-05, Final residual = 2.181205e-08, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 8.1303226e-05, Final residual = 1.7190079e-08, No Iterations 1
DILUPBiCG:  Solving for h, Initial residual = 1.3769818e-05, Final residual = 1.8025345e-09, No Iterations 1
Min/max T:-34.638404 939
GAMG:  Solving for p_rgh, Initial residual = 0.0041635193, Final residual = 8.7220279e-08, No Iterations 18
GAMG:  Solving for p_rgh, Initial residual = 3.0025266e-05, Final residual = 8.3696645e-08, No Iterations 7
GAMG:  Solving for p_rgh, Initial residual = 6.9780425e-06, Final residual = 9.4629866e-08, No Iterations 3
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 7.8066502e-11, global = -1.0715968e-11, cumulative = 1.0815598e-07
GAMG:  Solving for p_rgh, Initial residual = 2.6392854e-06, Final residual = 8.7769725e-08, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 9.0381004e-07, Final residual = 4.9359257e-08, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 3.9857535e-07, Final residual = 5.3627197e-08, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 4.4241536e-11, global = 2.0258428e-12, cumulative = 1.0815801e-07

Solving for solid region fibrothal_in
DICPCG:  Solving for h, Initial residual = 4.8427064e-06, Final residual = 5.6629409e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.9117983e-11, Final residual = 1.9117983e-11, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] -34.64088 max(T) [0 0 0 1 0 0 0] 823.55061

Solving for solid region solid_bricks
DICPCG:  Solving for h, Initial residual = 5.3881957e-06, Final residual = 1.8640995e-10, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.9768437e-10, Final residual = 1.9768437e-10, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300.00584 max(T) [0 0 0 1 0 0 0] 390.07814

Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 3.1120205e-06, Final residual = 3.4748029e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 3.5713957e-12, Final residual = 3.5713957e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 317.42391
ExecutionTime = 48517.36 s  ClockTime = 49699 s

Region: fluid Courant Number mean: 0.019875807 max: 0.29875958
Region: fibrothal_in Diffusion Number mean: 5.3693051e-08 max: 3.8684315e-07
Region: solid_bricks Diffusion Number mean: 2.453461e-06 max: 1.317393e-05
Region: unifrax_out Diffusion Number mean: 1.0442085e-07 max: 3.2171136e-07
deltaT = 0.0011417394
Time = 132.84016


Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 8.1108496e-05, Final residual = 2.5818077e-08, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 6.134127e-05, Final residual = 2.4355749e-08, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 8.5046122e-05, Final residual = 1.9803553e-08, No Iterations 1
DILUPBiCG:  Solving for h, Initial residual = 1.3767232e-05, Final residual = 1.8025597e-09, No Iterations 1
Min/max T:168.04889 939
GAMG:  Solving for p_rgh, Initial residual = 0.0041488398, Final residual = 9.7922006e-08, No Iterations 16
GAMG:  Solving for p_rgh, Initial residual = 2.5548778e-05, Final residual = 8.2376033e-08, No Iterations 7
GAMG:  Solving for p_rgh, Initial residual = 6.7243635e-06, Final residual = 5.251697e-08, No Iterations 4
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 4.3325191e-11, global = 5.3072732e-12, cumulative = 1.0816332e-07
GAMG:  Solving for p_rgh, Initial residual = 1.8993958e-06, Final residual = 6.9772195e-08, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 6.1908036e-07, Final residual = 8.0077444e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 2.4772369e-07, Final residual = 4.5438216e-08, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 3.7486014e-11, global = 1.2021921e-12, cumulative = 1.0816452e-07


Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 3.1120066e-06, Final residual = 3.4747852e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 3.5740577e-12, Final residual = 3.5740577e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 317.42429
ExecutionTime = 48517.93 s  ClockTime = 49700 s

Region: fluid Courant Number mean: 0.019875723 max: 0.29875153
Region: fibrothal_in Diffusion Number mean: 5.3693123e-08 max: 3.8684525e-07
Region: solid_bricks Diffusion Number mean: 2.453461e-06 max: 1.317393e-05
Region: unifrax_out Diffusion Number mean: 1.0442085e-07 max: 3.2171136e-07
deltaT = 0.0011417394
Time = 132.8413


Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 7.8970139e-05, Final residual = 2.3571827e-08, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 6.0058436e-05, Final residual = 2.2336877e-08, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 8.2795778e-05, Final residual = 1.7421106e-08, No Iterations 1
DILUPBiCG:  Solving for h, Initial residual = 1.3770425e-05, Final residual = 1.8043668e-09, No Iterations 1
Min/max T:-35.535871 939
GAMG:  Solving for p_rgh, Initial residual = 0.0041525003, Final residual = 8.3978618e-08, No Iterations 16
GAMG:  Solving for p_rgh, Initial residual = 2.0716891e-05, Final residual = 8.414588e-08, No Iterations 6
GAMG:  Solving for p_rgh, Initial residual = 5.9691193e-06, Final residual = 6.361722e-08, No Iterations 4
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 5.2482977e-11, global = -1.8655448e-12, cumulative = 1.0816265e-07
GAMG:  Solving for p_rgh, Initial residual = 1.6250719e-06, Final residual = 7.813847e-08, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 4.7865432e-07, Final residual = 6.8283963e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 1.8631846e-07, Final residual = 3.5284387e-08, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 2.9109187e-11, global = -2.3103795e-13, cumulative = 1.0816242e-07

Solving for solid region fibrothal_in
DICPCG:  Solving for h, Initial residual = 4.8424178e-06, Final residual = 5.6627448e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 7.5644313e-12, Final residual = 7.5644313e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] -35.538367 max(T) [0 0 0 1 0 0 0] 823.55579

Solving for solid region solid_bricks
DICPCG:  Solving for h, Initial residual = 5.3879905e-06, Final residual = 1.864035e-10, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.9767345e-10, Final residual = 1.9767345e-10, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300.00584 max(T) [0 0 0 1 0 0 0] 390.08076

Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 3.1119927e-06, Final residual = 3.4747675e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 3.5731187e-12, Final residual = 3.5731187e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 317.42467
ExecutionTime = 48518.51 s  ClockTime = 49700 s


Region: fluid Courant Number mean: 0.019875633 max: 0.29874413
Region: fibrothal_in Diffusion Number mean: 5.3693195e-08 max: 3.8684734e-07
Region: solid_bricks Diffusion Number mean: 2.453461e-06 max: 1.317393e-05
Region: unifrax_out Diffusion Number mean: 1.0442085e-07 max: 3.2171136e-07
deltaT = 0.0011417394
Regards,
Baran
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Old   September 1, 2015, 19:37
Default
  #9
Senior Member
 
Alex
Join Date: Oct 2013
Posts: 337
Rep Power: 17
zfaraday will become famous soon enough
Ok baran,

I guess that you are still using externalWallHeatFluxTemperature BC... If so, update your source code with the latest patches and corrections (in case you haven't done it for the last 3 months or so... If you installed OF 2.4.x less than 3 months ago it shouldn't be necessary...). Once you have uploaded it and recompiled it try using a similar specification for external boundaries to this one:

Code:
    myPatch
    {
        type            externalWallHeatFluxTemperature;
        kappa           fluidThermo;
        q               uniform 1000;
        Ta              uniform 300.0;
        h               uniform 10.0;
        thicknessLayers (0.1 0.2 0.3 0.4);
        kappaLayers     (1 2 3 4);
        value           uniform 300.0;
        kappaName       none;
        Qr              Qr;
        relaxation      1;    // try with lower values, using 1 will make no difference. Maybe 0.1 would do the trick...
    }
This piece of code I have taken it from here.

Hope it helps.

Best regards,

Alex
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Old   September 4, 2015, 08:31
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  #10
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baran
Join Date: Aug 2014
Posts: 45
Rep Power: 7
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Dear Alex,

I have changed the outer wall bc of externalWallHeatFluxTemperature as it is already available in of2.4 ...
Code:
    {
        type            externalWallHeatFluxTemperature;
        kappa           solidThermo;
        //q               uniform 1000;
        Ta              uniform 300.0;
        h               uniform 10.0;
        //thicknessLayers (0.1 0.2 0.3 0.4);
        //kappaLayers     (1 2 3 4);
        value           uniform 300.0;
        kappaName       none;
        Qr              Qr;
        relaxation      1;   
    }
Still I get the same problem.......and it is started diverging due to some low temperature in solid_bricks which have constant property of k= 0.15 j/kg K and other value also....
fvSolution...
Code:
solvers
{
    h
    {
        solver           PCG;
        preconditioner   DIC;
        tolerance        1e-06;
        relTol           0.1;
    }
    hFinal
    {
        $h;
        tolerance        1e-06;
        relTol           0;
    }
}

PIMPLE
{
    nNonOrthogonalCorrectors 2;
}
fvScheme...
Code:
ddtSchemes
{
    default Euler;
}

gradSchemes
{
    default         Gauss linear;
}

divSchemes
{
    default         none;
}

laplacianSchemes
{
    default         none;
    laplacian(alpha,h) Gauss linear limited 0.333;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         limited 0.333;
}

fluxRequired
{
    default         no;
}
this is log file of diverging section...
Code:
Region: fluid Courant Number mean: 0.011803868 max: 0.29978066
Region: fibrothal_in Diffusion Number mean: 5.984852e-08 max: 3.6395751e-07
Region: solid_bricks Diffusion Number mean: 4.325115e-08 max: 2.3223831e-07
Region: unifrax_out Diffusion Number mean: 1.2271976e-07 max: 3.7808866e-07
deltaT = 0.00134182
Time = 61.349217


Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 0.00020252946, Final residual = 1.0480067e-08, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.00022700634, Final residual = 4.9277215e-09, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.00021673457, Final residual = 8.2935081e-09, No Iterations 2
DILUPBiCG:  Solving for h, Initial residual = 7.0113698e-05, Final residual = 5.4885426e-10, No Iterations 2
Min/max T:314.12367 753
GAMG:  Solving for p_rgh, Initial residual = 0.0011703758, Final residual = 8.8669323e-08, No Iterations 6
GAMG:  Solving for p_rgh, Initial residual = 4.657791e-06, Final residual = 5.7582968e-08, No Iterations 3
GAMG:  Solving for p_rgh, Initial residual = 1.1551078e-06, Final residual = 4.3470744e-08, No Iterations 2
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 3.9981212e-10, global = -2.0513208e-11, cumulative = -1.7388678e-08
GAMG:  Solving for p_rgh, Initial residual = 1.3509646e-06, Final residual = 7.2930855e-08, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 2.5230028e-07, Final residual = 5.9736719e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 1.1260898e-07, Final residual = 4.3606164e-08, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 4.0105979e-10, global = -3.4002934e-11, cumulative = -1.7422681e-08

Solving for solid region fibrothal_in
DICPCG:  Solving for h, Initial residual = 1.3847821e-05, Final residual = 1.3047331e-11, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.3725991e-11, Final residual = 1.3725991e-11, No Iterations 0
DICPCG:  Solving for h, Initial residual = 1.3725991e-11, Final residual = 1.3725991e-11, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 611.48428

Solving for solid region solid_bricks
DICPCG:  Solving for h, Initial residual = 1.0430615e-05, Final residual = 6.5189609e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 9.8068229e-12, Final residual = 9.8068229e-12, No Iterations 0
DICPCG:  Solving for h, Initial residual = 9.8068229e-12, Final residual = 9.8068229e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 666.81513

Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 2.4035529e-05, Final residual = 1.605035e-11, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.544039e-09, Final residual = 1.544039e-09, No Iterations 0
DICPCG:  Solving for h, Initial residual = 1.544039e-09, Final residual = 1.544039e-09, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 300.03595
ExecutionTime = 16126.77 s  ClockTime = 16559 s

Region: fluid Courant Number mean: 0.011803874 max: 0.29977296
Region: fibrothal_in Diffusion Number mean: 5.9848554e-08 max: 3.6395834e-07
Region: solid_bricks Diffusion Number mean: 4.325115e-08 max: 2.3223831e-07
Region: unifrax_out Diffusion Number mean: 1.2271976e-07 max: 3.7808866e-07
deltaT = 0.00134182
Time = 61.350559


Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 0.0002025609, Final residual = 1.1910169e-08, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.00022700465, Final residual = 4.884998e-09, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.00021670343, Final residual = 8.4535848e-09, No Iterations 2
DILUPBiCG:  Solving for h, Initial residual = 7.0106796e-05, Final residual = 5.5296829e-10, No Iterations 2
                                                                                                      
LU Back substitute C matrix..
Min/max T:314.12101 753
GAMG:  Solving for p_rgh, Initial residual = 0.0011700388, Final residual = 7.9481395e-08, No Iterations 6
GAMG:  Solving for p_rgh, Initial residual = 4.6523857e-06, Final residual = 5.1471481e-08, No Iterations 3
GAMG:  Solving for p_rgh, Initial residual = 1.1486924e-06, Final residual = 4.0637e-08, No Iterations 2
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 3.7375369e-10, global = -4.3799329e-12, cumulative = -1.7427061e-08
GAMG:  Solving for p_rgh, Initial residual = 1.3509856e-06, Final residual = 6.9778436e-08, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 2.5777917e-07, Final residual = 5.2959357e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 1.065836e-07, Final residual = 3.6159249e-08, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 3.3257513e-10, global = -3.1279595e-11, cumulative = -1.745834e-08

Solving for solid region fibrothal_in
DICPCG:  Solving for h, Initial residual = 1.3848359e-05, Final residual = 1.3046006e-11, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.5699743e-11, Final residual = 1.5699743e-11, No Iterations 0
DICPCG:  Solving for h, Initial residual = 1.5699743e-11, Final residual = 1.5699743e-11, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 611.4786

Solving for solid region solid_bricks
DICPCG:  Solving for h, Initial residual = 1.0418483e-05, Final residual = 6.5202524e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 2.4807543e-09, Final residual = 2.4807543e-09, No Iterations 0
DICPCG:  Solving for h, Initial residual = 2.4807543e-09, Final residual = 2.4807543e-09, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 289.72511 max(T) [0 0 0 1 0 0 0] 649.88563

Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 2.4034686e-05, Final residual = 1.6049802e-11, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.6219618e-09, Final residual = 1.6219618e-09, No Iterations 0
DICPCG:  Solving for h, Initial residual = 1.6219618e-09, Final residual = 1.6219618e-09, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 300.03596
ExecutionTime = 16127.5 s  ClockTime = 16560 s

Region: fluid Courant Number mean: 0.011803878 max: 0.29976523
Region: fibrothal_in Diffusion Number mean: 5.9848588e-08 max: 3.6395917e-07
Region: solid_bricks Diffusion Number mean: 4.325115e-08 max: 2.3223831e-07
Region: unifrax_out Diffusion Number mean: 1.2271976e-07 max: 3.7808866e-07
deltaT = 0.00134182
Time = 61.351901


Solving for fluid region fluid
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Ux, Initial residual = 0.000202575, Final residual = 1.1953834e-08, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.00022699901, Final residual = 4.9589681e-09, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.00021670665, Final residual = 8.6043666e-09, No Iterations 2
DILUPBiCG:  Solving for h, Initial residual = 7.0163301e-05, Final residual = 5.5663264e-10, No Iterations 2
Min/max T:289.72512 753
GAMG:  Solving for p_rgh, Initial residual = 0.0011745932, Final residual = 9.461503e-08, No Iterations 23
GAMG:  Solving for p_rgh, Initial residual = 1.3703751e-05, Final residual = 9.2266387e-08, No Iterations 5
GAMG:  Solving for p_rgh, Initial residual = 3.2030153e-06, Final residual = 7.2234752e-08, No Iterations 3
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 6.6436148e-10, global = -1.1345981e-10, cumulative = -1.75718e-08
GAMG:  Solving for p_rgh, Initial residual = 2.1936572e-06, Final residual = 7.8329574e-08, No Iterations 3
GAMG:  Solving for p_rgh, Initial residual = 5.4352731e-07, Final residual = 9.250977e-08, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 2.3308027e-07, Final residual = 5.8853582e-08, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (fluid): sum local = 5.4130436e-10, global = 5.585416e-11, cumulative = -1.7515946e-08

                                                                                                                                                              
Solving for solid region fibrothal_in
DICPCG:  Solving for h, Initial residual = 1.3847885e-05, Final residual = 1.3045515e-11, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.3991418e-11, Final residual = 1.3991418e-11, No Iterations 0
DICPCG:  Solving for h, Initial residual = 1.3991418e-11, Final residual = 1.3991418e-11, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 611.48274

Solving for solid region solid_bricks
DICPCG:  Solving for h, Initial residual = 1.0418394e-05, Final residual = 6.519972e-12, No Iterations 1
DICPCG:  Solving for h, Initial residual = 9.8457579e-12, Final residual = 9.8457579e-12, No Iterations 0
DICPCG:  Solving for h, Initial residual = 9.8457579e-12, Final residual = 9.8457579e-12, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 289.71756 max(T) [0 0 0 1 0 0 0] 649.89343

Solving for solid region unifrax_out
DICPCG:  Solving for h, Initial residual = 2.4034443e-05, Final residual = 1.6049873e-11, No Iterations 1
DICPCG:  Solving for h, Initial residual = 1.6956056e-09, Final residual = 1.6956056e-09, No Iterations 0
DICPCG:  Solving for h, Initial residual = 1.6956056e-09, Final residual = 1.6956056e-09, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 300 max(T) [0 0 0 1 0 0 0] 300.03596
ExecutionTime = 16127.98 s  ClockTime = 16561 s

I can't understand why suddenly there is low temperature in solid_bricks....please suggest something...

Regards,
Baran
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