Conjugate heat transfer- chtMultiRegionFoam Divergence after changing mesh size

sandymech1 · March 9, 2018, 12:11

Hi to All,

I have setup case where it involves transient conjugate heat transfer with heat generation inside solid cylinder (solidheater), which exchanges heat with fluid (fluidaround) through natural convection. Whole set up can be found in attached zip file.

Given setup case works fine with mesh divisions xm-40, ym-40,zm-100 (blockMeshDict). As soon as I changes any of this parameter, it diverges (Specifically residual in continuity). I tried with changing relaxation factors, solvers etc, but still it diverges ( I have attached log of solvers ). I am not sure,where I am going wrong. It is kind request to you all, please help me in this regard .

logfile

HTML Code:

 Pimple iteration 0

Solving for fluid region fluidaround
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.29933612, Final residual =                          3.1524045e-05, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.29488843, Final residual =                          2.6319012e-05, No Iterations 1
DILUPBiCGStab:  Solving for Uz, Initial residual = 0.49750534, Final residual =                          4.1921594e-05, No Iterations 1
DILUPBiCGStab:  Solving for h, Initial residual = 0.73364446, Final residual = 3                         .344238e-05, No Iterations 1
Min/max T:298.2049 300.79852
GAMG:  Solving for p_rgh, Initial residual = 0.73284638, Final residual = 0.0025                         169295, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
time step continuity errors (fluidaround): sum local = 0.14139322, global = -0.1                         4138582, cumulative = -0.056385678
GAMG:  Solving for p_rgh, Initial residual = 0.79452024, Final residual = 0.0026                         745088, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
time step continuity errors (fluidaround): sum local = 0.14107228, global = -0.1                         4105376, cumulative = -0.19743944

Solving for solid region solidheater
DICPCG:  Solving for h, Initial residual = 0.95211619, Final residual = 1.049635                         7e-07, No Iterations 3
Min/max T:300.00158 300.00192
ExecutionTime = 410.99 s  ClockTime = 411 s

Region: fluidaround Courant Number mean: 0.0080870968 max: 0.91038173
Region: solidheater Diffusion Number mean: 0.025188926 max: 0.1066149
deltaT = 8.7806546e-06
Time = 0.00821582

Pimple iteration 0

Solving for fluid region fluidaround
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.5281099, Final residual = 4                         .7080012e-05, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.52569877, Final residual =                          3.6867719e-05, No Iterations 1
DILUPBiCGStab:  Solving for Uz, Initial residual = 0.76869711, Final residual =                          5.0486841e-05, No Iterations 1
DILUPBiCGStab:  Solving for h, Initial residual = 0.99525026, Final residual = 3                         .780045e-05, No Iterations 1
Min/max T:274.37304 300.00192
GAMG:  Solving for p_rgh, Initial residual = 0.67924439, Final residual = 0.0017                         981522, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
time step continuity errors (fluidaround): sum local = 0.20812231, global = 0.20                         811415, cumulative = 0.010674711
GAMG:  Solving for p_rgh, Initial residual = 0.90571687, Final residual = 0.0023                         360085, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
time step continuity errors (fluidaround): sum local = 0.20780481, global = 0.20                         778441, cumulative = 0.21845912

Solving for solid region solidheater
DICPCG:  Solving for h, Initial residual = 0.91721184, Final residual = 1.462930                         9e-07, No Iterations 3
Min/max T:299.99629 300.00179
ExecutionTime = 413.97 s  ClockTime = 414 s

Region: fluidaround Courant Number mean: 0.016810218 max: 1.1516419
Region: solidheater Diffusion Number mean: 0.02628284 max: 0.11124501
deltaT = 7.2430699e-06
Time = 0.00822306

Pimple iteration 0

Solving for fluid region fluidaround
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.46516049, Final residual =                          5.6102159e-05, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.45751446, Final residual =                          4.6068563e-05, No Iterations 1
DILUPBiCGStab:  Solving for Uz, Initial residual = 0.64284599, Final residual =                          6.6475103e-05, No Iterations 1
DILUPBiCGStab:  Solving for h, Initial residual = 0.8155895, Final residual = 4.                         2629411e-05, No Iterations 1
Min/max T:295.31937 323.58789
GAMG:  Solving for p_rgh, Initial residual = 0.73538149, Final residual = 0.0022                         779021, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
time step continuity errors (fluidaround): sum local = 0.39435278, global = -0.3                         9433851, cumulative = -0.17587939
GAMG:  Solving for p_rgh, Initial residual = 0.82536424, Final residual = 0.0025                         182738, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
time step continuity errors (fluidaround): sum local = 0.3935059, global = -0.39                         34684, cumulative = -0.56934778

Solving for solid region solidheater
DICPCG:  Solving for h, Initial residual = 0.86794349, Final residual = 5.899461                         4e-08, No Iterations 3
Min/max T:300.00179 300.00505
ExecutionTime = 416.92 s  ClockTime = 417 s

Region: fluidaround Courant Number mean: 0.025390934 max: 2.6728342
Region: solidheater Diffusion Number mean: 0.021680439 max: 0.091764845
deltaT = 2.5743882e-06
Time = 0.00822564

Pimple iteration 0

Solving for fluid region fluidaround
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.15193, Final residual = 1.2                         246081e-05, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.15240949, Final residual =                          9.5458813e-06, No Iterations 1
DILUPBiCGStab:  Solving for Uz, Initial residual = 0.34848201, Final residual =                          2.1061955e-05, No Iterations 1
DILUPBiCGStab:  Solving for h, Initial residual = 0.75616335, Final residual = 2                         .8186223e-05, No Iterations 1
Min/max T:293.78757 303.6014
GAMG:  Solving for p_rgh, Initial residual = 0.79713681, Final residual = 4.1911                         299e-05, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
time step continuity errors (fluidaround): sum local = 0.54974847, global = 0.54                         974847, cumulative = -0.01959931
GAMG:  Solving for p_rgh, Initial residual = 0.86665115, Final residual = 4.5493                         363e-05, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
time step continuity errors (fluidaround): sum local = 0.54970224, global = 0.54                         970219, cumulative = 0.53010288

Solving for solid region solidheater
DICPCG:  Solving for h, Initial residual = 0.66410935, Final residual = 1.600647                         9e-09, No Iterations 3
Min/max T:300.00013 300.00179
ExecutionTime = 419.92 s  ClockTime = 420 s

Region: fluidaround Courant Number mean: 0.002196658 max: 0.45327734
Region: solidheater Diffusion Number mean: 0.0077058301 max: 0.032615774
deltaT = 3.0892138e-06
Time = 0.00822872

Pimple iteration 0

Solving for fluid region fluidaround
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.94956143, Final residual =                          3.8893826e-05, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.97620096, Final residual =                          3.102514e-05, No Iterations 1
DILUPBiCGStab:  Solving for Uz, Initial residual = 0.93120652, Final residual =                          1.799285e-05, No Iterations 1
DILUPBiCGStab:  Solving for h, Initial residual = 0.99244424, Final residual = 1                         .9158005e-05, No Iterations 1
Min/max T:295.64107 400
GAMG:  Solving for p_rgh, Initial residual = 0.75839625, Final residual = 0.0012                         40774, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
time step continuity errors (fluidaround): sum local = 1.6407302, global = -1.64                         07297, cumulative = -1.1106268
GAMG:  Solving for p_rgh, Initial residual = 0.81773179, Final residual = 0.0012                         961357, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
time step continuity errors (fluidaround): sum local = 1.6393499, global = -1.63                         93403, cumulative = -2.7499671

Solving for solid region solidheater
DICPCG:  Solving for h, Initial residual = 0.89434667, Final residual = 1.943862                         6e-09, No Iterations 3
Min/max T:300.0018 300.03392
ExecutionTime = 422.89 s  ClockTime = 423 s

Region: fluidaround Courant Number mean: 0.046624434 max: 1.6295532
Region: solidheater Diffusion Number mean: 0.0092468405 max: 0.03913827
deltaT = 1.8009552e-06
Time = 0.00823053

Pimple iteration 0

Solving for fluid region fluidaround
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterati                         ons 0
DILUPBiCGStab:  Solving for Ux, Initial residual = 0.063946568, Final residual =                          1.7525006e-05, No Iterations 1
DILUPBiCGStab:  Solving for Uy, Initial residual = 0.066616981, Final residual =                          1.2939822e-05, No Iterations 1
DILUPBiCGStab:  Solving for Uz, Initial residual = 0.22543798, Final residual =                          3.8261272e-05, No Iterations 1
DILUPBiCGStab:  Solving for h, Initial residual = 0.76802606, Final residual = 0                         .00010738033, No Iterations 1
Min/max T:300 359.23807
[3] #0  Foam::error::printStack(Foam::Ostream&) at ??:?
[3] #1  Foam::sigFpe::sigHandler(int) at ??:?
[3] #2  ? in "/lib64/libc.so.6"
[3] #3  Foam::GAMGSolver::scale(Foam::Field<double>&, Foam::Field<double>&, Foam                         ::lduMatrix const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList                         <Foam::lduInterfaceField const> const&, Foam::Field<double> const&, unsigned cha                         r) const at ??:?
[3] #4  Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMatrix::smoother> const&                         , Foam::Field<double>&, Foam::Field<double> const&, Foam::Field<double>&, Foam::                         Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&                         , Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, un                         signed char) const at ??:?
[3] #5  Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&                         , unsigned char) const at ??:?
[3] #6  Foam::fvMatrix<double>::solveSegregated(Foam::dictionary const&) at ??:?
[3] #7  Foam::fvMatrix<double>::solve(Foam::dictionary const&) at ??:?
[3] #8  ? at ??:?
[3] #9  __libc_start_main in "/lib64/libc.so.6"
[3] #10  ? at ??:?

blockMeshdict file

Code:

 convertToMeters 1;

//Complete Domain Dimension 
R 0.10;
L 0.090;
L2 0.01;

//Number of divisions in three directions
xm 40;
ym 40;
zm 100;

//Miscellaneous Calculations
PI 3.14159265;
radAngle #calc "degToRad(45.0)";
AP #calc "$R*sin($radAngle)";
Rmin #calc "-1.0*$R"; 
APmin #calc "-1*$AP";
L1 #calc "-1*$L2";


vertices        

(

    (0 0 $L1) 
    ($R 0 $L1) 
    (0 $R $L1)
    ($Rmin 0 $L1)
    (0 $Rmin $L1)    
    (0 0 $L) 
    ($R 0 $L)
    (0 $R $L)   
    ($Rmin 0 $L)
    (0 $Rmin $L)
    	
);



blocks          

(

    hex (0 1 2 0 5 6 7 5) ($xm $ym $zm) simpleGrading (1 1 1)
    hex (0 2 3 0 5 7 8 5) ($xm $ym $zm) simpleGrading (1 1 1)
    hex (0 3 4 0 5 8 9 5) ($xm $ym $zm) simpleGrading (1 1 1)
    hex (0 4 1 0 5 9 6 5) ($xm $ym $zm) simpleGrading (1 1 1)

  //  hex (4 1 2 3 9 6 7 8) (40 40 4) simpleGrading (1 1 1)

);



edges           

(

    arc 1 2 ($AP $AP $L1)
    arc 2 3 ($APmin $AP $L1)
    arc 3 4 ($APmin $APmin $L1)
    arc 4 1 ($AP $APmin $L1)

    arc 6 7 ($AP $AP $L)
    arc 7 8 ($APmin $AP $L)
    arc 8 9 ($APmin $APmin $L)
    arc 9 6 ($AP $APmin $L)

   // arc 6 9 (0.078 0.078 0.8)

   // arc 7 8 (0.848 0.848 0.8)

);



boundary

(



   top 

    {

        type wall;

        faces

        (

           	 (5 6 7 5)
		 (5 7 8 5)
 	  	 (5 8 9 5)
 	    	 (5 9 6 5)
 	

           // (6 7 8 9)

        );

    }

    

    bottom

    {

         type wall;

         faces

         (

        	(0 1 2 0)
		(0 2 3 0)
		(0 3 4 0)
		(0 4 1 0)

           // (0 1 4 0)

         );

    }   



  lateral 

    {

        type wall;

        faces

        (

        	(1 2 7 6)
		(2 3 8 7)
		(3 4 9 8)
		(4 1 6 9)


	

        );

    }   



    


);



mergePatchPairs 

(

);


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

fluidaround/fvSolution

Code:

solvers
{
    rho
    {
        solver          PCG;
        preconditioner  DIC;
        tolerance       1e-7;
        relTol          0.1;
    }

    rhoFinal
    {
        $rho;
        tolerance       1e-7;
        relTol          0.1;
    }

    p_rgh
    {
        solver           GAMG;
        tolerance        1e-7;
        relTol           0.1;

	  smoother         GaussSeidel;

    }

    p_rghFinal
    {
        $p_rgh;
        tolerance        1e-7;
        relTol           0.1;
    }

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

    "(U|h|k|epsilon|R)Final"
    {
        $U;
        tolerance        1e-7;
        relTol           0.1;
    }
}

PIMPLE
{
    momentumPredictor   yes;
    nCorrectors         2;
    nNonOrthogonalCorrectors 0;
}

relaxationFactors
{
    equations
    {
        "h.*"           0.7;
        "U.*"           1;
    }
}

ControlDict

Code:

application     chtMultiRegionFoam;

startFrom       latestTime;

startTime       0.00001;

stopAt          endTime;

endTime         5;

deltaT          0.00001;

writeControl    adjustableRunTime;

writeInterval   0.1;

purgeWrite      0;

writeFormat     ascii;

writePrecision  8;

writeCompression off;

timeFormat      general;

timePrecision   6;

runTimeModifiable yes;

maxCo           0.95;

// Maximum diffusion number
maxDi           10.0;

adjustTimeStep  yes;

piu58 · March 10, 2018, 13:09

Dear Sandy,

I downloaded your case and started it. It works after a few modifications in blockMesh. I cannot see any heat sources in it, but that may be because I don't understand all the things your scripts make.

If I/we should help you I ask you to reduce the case to the simplest one: Nu 256 processors (which I don't have), not indirect setting of boundary conditions, no indirect determining the solver.

Rather in the way a tutorial is, with all b.c. set ready to use
- after blockMesh I can llok at the b.c. with paraFoam
- I may call the solver directly (in your case it should be chtMultiRegionFoam)
- I can look at the results again with parafoam

Thank you.

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March 10, 2018, 13:09		#2
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	Dear Sandy, I downloaded your case and started it. It works after a few modifications in blockMesh. I cannot see any heat sources in it, but that may be because I don't understand all the things your scripts make. If I/we should help you I ask you to reduce the case to the simplest one: Nu 256 processors (which I don't have), not indirect setting of boundary conditions, no indirect determining the solver. Rather in the way a tutorial is, with all b.c. set ready to use - after blockMesh I can llok at the b.c. with paraFoam - I may call the solver directly (in your case it should be chtMultiRegionFoam) - I can look at the results again with parafoam Thank you. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)