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 baran_foam August 19, 2015 06:48

Problem with chtMultiregionFoam radiation boundary condition

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..??

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?

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.

 baran_foam August 20, 2015 10:29

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

 wyldckat August 20, 2015 15:30

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

 baran_foam August 24, 2015 02:17

Greeting All!!!
@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

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

 baran_foam August 26, 2015 08:21

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

 baran_foam August 31, 2015 07:02

1 Attachment(s)
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

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

 baran_foam September 4, 2015 08:31

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... :confused: :(

Regards,
Baran

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