CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

Divergence after high number of iterations

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   November 14, 2013, 05:22
Default Divergence after high number of iterations
  #1
New Member
 
erik gustafsson
Join Date: Oct 2013
Posts: 19
Rep Power: 2
guserik is on a distinguished road
Hello
I got a really frustrating problem. I have established a procedure for simulating conjugated heat transfer between fluid and solid with chtMultiRegionSimpleFoam. My models have always worked but now when i have a really fine model everything crash after around 600 iterations. Until this the solution converge good and the all residuals are less than 0.001. Is there anyone who knows how to solve this problem?
guserik is offline   Reply With Quote

Old   November 14, 2013, 05:55
Default
  #2
Senior Member
 
akidess's Avatar
 
Anton Kidess
Join Date: May 2009
Location: Delft, Netherlands
Posts: 912
Rep Power: 16
akidess will become famous soon enough
How to give enough info to get help
__________________
*On twitter @akidTwit
*Spend as much time formulating your questions as you expect people to spend on their answer.
*Check out the scientific computing exchange http://scicomp.stackexchange.com
akidess is offline   Reply With Quote

Old   November 14, 2013, 07:08
Default
  #3
New Member
 
erik gustafsson
Join Date: Oct 2013
Posts: 19
Rep Power: 2
guserik is on a distinguished road
My mesh seems ok when i runned the checkMesh. Since i run it on our cluster i dont get t

Code:
Time = 585

Solving for fluid region fluid
DILUPBiCG:  Solving for Ux, Initial residual = 0.0002279771, Final residual = 7.889007e-06, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 0.0003652472, Final residual = 9.324946e-06, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 0.001360254, Final residual = 3.218115e-05, No Iterations 1
GAMG:  Solving for h, Initial residual = 0.0004399999, Final residual = 9.285599e-07, No Iterations 2
Min/max T:337.9997 341.8999
GAMG:  Solving for p_rgh, Initial residual = 0.002022551, Final residual = 1.222316e-05, No Iterations 5
GAMG:  Solving for p_rgh, Initial residual = 0.0005562866, Final residual = 5.387977e-06, No Iterations 3
time step continuity errors : sum local = 0.0563915, global = -8.993817e-05, cumulative = -62.71551
Min/max rho:1054 1054
DILUPBiCG:  Solving for epsilon, Initial residual = 0.0849624, Final residual = 0.0002585619, No Iterations 1
bounding epsilon, min: -26.73187 max: 15466.52 average: 2.532161
DILUPBiCG:  Solving for k, Initial residual = 0.00134489, Final residual = 1.96022e-05, No Iterations 1
Solving for solid region solid
DICPCG:  Solving for h, Initial residual = 0.0003222915, Final residual = 9.867308e-06, No Iterations 2
DICPCG:  Solving for h, Initial residual = 0.0003249724, Final residual = 1.023341e-05, No Iterations 2
Min/max T:min(T) [0 0 0 1 0 0 0] 338 max(T) [0 0 0 1 0 0 0] 346.6688
ExecutionTime = 3132.69 s  ClockTime = 3139 s
Time = 586

Solving for fluid region fluid
DILUPBiCG:  Solving for Ux, Initial residual = 0.01086879, Final residual = 4.23718e-09, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 0.1005754, Final residual = 1.090088e-08, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 0.176239, Final residual = 1.885607e-08, No Iterations 1
GAMG:  Solving for h, Initial residual = 0.1106389, Final residual = 0.001035424, No Iterations 1
Min/max T:337.9997 341.9038
GAMG:  Solving for p_rgh, Initial residual = 0.002115051, Final residual = 2.05201e-05, No Iterations 5
GAMG:  Solving for p_rgh, Initial residual = 0.9963446, Final residual = 0.004556654, No Iterations 8
time step continuity errors : sum local = 13971.99, global = -10.3378, cumulative = -73.05331
Min/max rho:1054 1054
DILUPBiCG:  Solving for epsilon, Initial residual = 0.3303189, Final residual = 0.01969804, No Iterations 1
bounding epsilon, min: -22.85394 max: 36519.9 average: 2.713533
DILUPBiCG:  Solving for k, Initial residual = 0.9996548, Final residual = 0.008013062, No Iterations 1
Solving for solid region solid
DICPCG:  Solving for h, Initial residual = 0.0003217334, Final residual = 9.850451e-06, No Iterations 2
DICPCG:  Solving for h, Initial residual = 0.0003244086, Final residual = 1.021595e-05, No Iterations 2
Min/max T:min(T) [0 0 0 1 0 0 0] 338 max(T) [0 0 0 1 0 0 0] 346.6729
ExecutionTime = 3138.66 s  ClockTime = 3145 s
Time = 587

Solving for fluid region fluid
DILUPBiCG:  Solving for Ux, Initial residual = 0.2542555, Final residual = 0.003127732, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 0.229307, Final residual = 0.001091918, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 0.3299211, Final residual = 0.001057152, No Iterations 1
GAMG:  Solving for h, Initial residual = 0.9999995, Final residual = 0.001948424, No Iterations 3
Min/max T:-1.192378e+07 3671610
GAMG:  Solving for p_rgh, Initial residual = 0.9833382, Final residual = 0.004657309, No Iterations 20
GAMG:  Solving for p_rgh, Initial residual = 0.5844197, Final residual = 0.003799768, No Iterations 4
time step continuity errors : sum local = 89309.59, global = -30.79077, cumulative = -103.8441
Min/max rho:1054 1054
DILUPBiCG:  Solving for epsilon, Initial residual = 0.9930006, Final residual = 0.0390609, No Iterations 2
bounding epsilon, min: -25.73662 max: 6.531648e+09 average: 41468.83
DILUPBiCG:  Solving for k, Initial residual = 0.999766, Final residual = 0.01822295, No Iterations 2
Solving for solid region solid
DICPCG:  Solving for h, Initial residual = 0.01450694, Final residual = 0.0007850409, No Iterations 2
DICPCG:  Solving for h, Initial residual = 0.01102243, Final residual = 0.0005736408, No Iterations 2
Min/max T:min(T) [0 0 0 1 0 0 0] -669.9338 max(T) [0 0 0 1 0 0 0] 13726.58
ExecutionTime = 3146.34 s  ClockTime = 3152 s
Time = 588

Solving for fluid region fluid
DILUPBiCG:  Solving for Ux, Initial residual = 0.2112948, Final residual = 0.001279738, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 0.1900647, Final residual = 0.001276108, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 0.2537446, Final residual = 0.0007415269, No Iterations 1
GAMG:  Solving for h, Initial residual = 0.6227222, Final residual = 0.0004394558, No Iterations 2
[15] 
[15] --> FOAM FATAL ERROR: 
[15] Maximum number of iterations exceeded
[15] 
[15]     From function thermo<Thermo, Type>::T(scalar f, scalar T0, scalar (thermo<Thermo, Type>::*F)(const scalar) const, scalar (thermo<Thermo, Type>::*dFdT)(const scalar) const, scalar (thermo<Thermo, Type>::*limit)(const scalar) const) const
[15]     in file /disk/sw/OpenFOAM/OpenFOAM-2.2.2/src/thermophysicalModels/specie/lnInclude/thermoI.H at line 76.
[15]
After this step i got the error message Maximal number of iterations exceeded.

My fv solution is
Code:
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
solvers
{
    rho
    {
        solver          PCG
        preconditioner  DIC;
        tolerance       1e-7;
        relTol          0;
    }
    p
    {
        solver          PCG;
        preconditioner  DIC;
        tolerance       1e-06;
        relTol          0.01;
    }
    U
    {
        solver          PBiCG;
        preconditioner  DILU;
        tolerance       1e-05;
        relTol          0.1;
    }
    p_rgh
    {
        solver           GAMG;
        tolerance        1e-7;
        relTol           0.01;
        smoother         GaussSeidel;
        cacheAgglomeration true;
        nCellsInCoarsestLevel 10;
        agglomerator     faceAreaPair;
        mergeLevels      1;
        maxIter          100;
    }
    h
    {
        solver           GAMG;
        tolerance        1e-7;
        relTol           0.01;
        smoother         GaussSeidel;
        cacheAgglomeration true;
        nCellsInCoarsestLevel 10;
        agglomerator     faceAreaPair;
        mergeLevels      1;
        maxIter          100;
    }
    k
    {
        solver          PBiCG;
        preconditioner  DILU;
        tolerance       1e-05;
        relTol          0.1;
    }
    epsilon
    {
        solver          PBiCG;
        preconditioner  DILU;
        tolerance       1e-05;
        relTol          0.1;
    }
    R
    {
        solver          PBiCG;
        preconditioner  DILU;
        tolerance       1e-05;
        relTol          0.1;
    }
    "(k|epsilon)"
    {
        solver           PBiCG;
        preconditioner   DILU;
        tolerance        1e-7;
        relTol           0.1;
    }
}
SIMPLE
{
    momentumPredictor on;
    nNonOrthogonalCorrectors 0;
    pRefCell        0;
    pRefValue       100000;
    rhoMin          rhoMin [1 -3 0 0 0] 1054;
    rhoMax          rhoMax [1 -3 0 0 0] 1054;
}
relaxationFactors
{
    fields
    {
        rho             1;
        p_rgh           0.7;
    }
    equations
    {
        U               0.3;
        h               0.7;
        nuTilda         0.7;
        k               0.7;
        epsilon         0.7;
        omega           0.7;
        "ILambda.*"     0.7;
    }
}
// ************************************************************************* //
My fvSchemes

Code:
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
ddtSchemes
{
    default     steadyState;
}
gradSchemes
{
    default         Gauss linear;
    grad(p)         Gauss linear;
    grad(U)         Gauss linear;
}

divSchemes
{
    default         none;
    div(phi,U)      bounded Gauss upwind;
    div(phi,K)      bounded Gauss upwind;
    div(phi,h)      bounded Gauss upwind;
    div(phi,k)      bounded Gauss upwind;
    div(phi,K)      bounded Gauss upwind;
    div(phi,epsilon) bounded Gauss upwind;
    div(phi,R)      bounded Gauss upwind;
    div(R)          Gauss linear;
    div((muEff*dev2(T(grad(U))))) Gauss linear;
}
 
 
laplacianSchemes
{
    default         none;
    laplacian(muEff,U) Gauss linear corrected;
    laplacian(Dp,p_rgh) Gauss linear corrected;
    laplacian(alphaEff,h)  Gauss linear corrected;
    laplacian(DkEff,k) Gauss linear corrected;
    laplacian(DepsilonEff,epsilon) Gauss linear corrected;
    laplacian(DREff,R) Gauss linear corrected;
}
interpolationSchemes
{
    default         linear;
    interpolate(U)  linear;
}
snGradSchemes
{
    default         corrected;
}
fluxRequired
{
    default         yes;
    p_rgh;
 T;
}

But i cant really figure out what is my problem since i runned the simulations before and then it's always converged. The only difference now is that my grid is finer and i switched properties from water to water/glycol
guserik is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Simulation seems to converge but crashes suddenly xxxx OpenFOAM 16 September 12, 2014 08:07
calculation stops after few time steps sivakumar OpenFOAM Running, Solving & CFD 7 March 17, 2013 07:37
pisoFoam - unstable pressure residual Industrial_CFD OpenFOAM Running, Solving & CFD 21 February 24, 2013 15:39
Error while running rhoPisoFoam.. nileshjrane OpenFOAM Running, Solving & CFD 8 August 26, 2010 12:50
Differences between serial and parallel runs carsten OpenFOAM Bugs 11 September 12, 2008 11:16


All times are GMT -4. The time now is 19:40.