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Old   March 6, 2016, 23:26
Default Problem with chtMultiRegionSimpleFoam
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Ali
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Hello everyone,

This is my first time trying to model a multi region problem in OF. I'm trying to model the COMSOL's heat exchanger problem using OF. I did model the example in the Fluent and everything is working fine.

Now I'm trying to run the same model in OF and I have problem with defining the boundary conditions. The energy equation explodes immediately and solver dumps the solution. I was wondering if anyone can take a look at my BC and trying to see if can help me find out what I am defining wrong.

The link below is my case folder.

https://drive.google.com/file/d/0B8L...ew?usp=sharing

I would appreciate any helps/hints to solve this problem.

Thank you in advance.
Ali

Last edited by alib022; March 22, 2016 at 12:17.
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Old   March 22, 2016, 12:19
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Anyone?

Any help would be highly appreciated!
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Old   March 23, 2016, 15:18
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Hi Ali,

Take a look at the thread below if you really want to get some help.

how to give enough info to get help

Best regards,

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   March 23, 2016, 22:57
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Alex,

Thank you for the guide, no wonder I didnt get anything!

ok here is my mesh:
m
and here is the report of the checkMesh:
Code:
/*---------------------------------------------------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
Build  : 3.0.1-119cac7e8750
Exec   : checkMesh
Date   : Mar 23 2016
Time   : 20:54:34
Host   : "ale-Lenovo-Z40-70"
PID    : 14145
Case   : /home/ale/Desktop/he
nProcs : 1
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster
allowSystemOperations : Allowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create polyMesh for time = 0

Time = 0

Mesh stats
    points:           839563
    faces:            7787072
    internal faces:   6833624
    cells:            3655174
    faces per cell:   4
    boundary patches: 22
    point zones:      0
    face zones:       3
    cell zones:       3

Overall number of cells of each type:
    hexahedra:     0
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    3655174
    polyhedra:     0

Checking topology...
    Boundary definition OK.
    Cell to face addressing OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
   *Number of regions: 3
    The mesh has multiple regions which are not connected by any face.
  <<Writing region information to "0/cellToRegion"
  <<Writing region 0 with 1816924 cells to cellSet region0
  <<Writing region 1 with 810203 cells to cellSet region1
  <<Writing region 2 with 1028047 cells to cellSet region2

Checking patch topology for multiply connected surfaces...
    Patch               Faces    Points   Surface topology                  
    wall_sheets:005     6074     3487     ok (non-closed singly connected)  
    wall_sheets:005-shadow6074     3487     ok (non-closed singly connected)  
    symmet:004          4463     4097     ok (non-closed singly connected)  
    symmet:003          8541     5042     ok (non-closed singly connected)  
    inner_wall:002      8393     4365     ok (non-closed singly connected)  
    inner_wall:002-shadow8393     4365     ok (non-closed singly connected)  
    inner_wall          18182    9483     ok (non-closed singly connected)  
    inner_wall-shadow   18182    9483     ok (non-closed singly connected)  
    outer_wall          28716    14596    ok (non-closed singly connected)  
    inlet_air           149      97       ok (non-closed singly connected)  
    outlet_water        171      111      ok (non-closed singly connected)  
    inlet_water         164      106      ok (non-closed singly connected)  
    outlet_air          141      93       ok (non-closed singly connected)  
    symmet              13073    7501     ok (non-closed singly connected)  
    wall_buffers        14915    9184     ok (non-closed singly connected)  
    wall_buffers-shadow 14915    9184     ok (non-closed singly connected)  
    wall_sheets         5326     3292     ok (non-closed singly connected)  
    wall_sheets-shadow  5326     3292     ok (non-closed singly connected)  
    wall_outsideubes    230714   118113   ok (non-closed singly connected)  
    wall_outsideubes-shadow230714   118113   ok (non-closed singly connected)  
    wall_insidetubes    165411   83728    ok (non-closed singly connected)  
    wall_insidetubes-shadow165411   83728    ok (non-closed singly connected)  

Checking geometry...
    Overall domain bounding box (-375 -130 -105) (375 130 4.039243e-08)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (6.910344e-20 -1.516309e-17 1.878536e-16) OK.
    Max cell openness = 2.891113e-16 OK.
    Max aspect ratio = 5.910575 OK.
    Minimum face area = 0.2897532. Maximum face area = 88.66169.  Face area magnitudes OK.
    Min volume = 0.09708428. Max volume = 245.6505.  Total volume = 1.155842e+07.  Cell volumes OK.
    Mesh non-orthogonality Max: 60.60822 average: 18.27468
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 0.6922095 OK.
    Coupled point location match (average 0) OK.

Mesh OK.

End
so as you can see I'm trying to model a multi region problem (fluid: air_domain water_domain solid: solid_domain)

I have to mention that I have multiple coupled patches.

About the fvsolution I'm using identical solvers for air and water as below:

Code:
solvers
{
    p_rgh
    {
        solver           GAMG;
        tolerance        1e-7;
        relTol           0.01;

        smoother         DIC;

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

        maxIter          100;
    }

    "(U|h|e|k|epsilon)"
    {
     solver          PBiCG;
        preconditioner  DILU;
        tolerance       1e-6;
        relTol          0.1;
       //  solver smoothSolver;
      //  smoother symGaussSeidel;
      //  tolerance        1e-7;
       // relTol          0.01;
    }
}
and for the solid:

Code:
solvers
{
    h
    {
        solver           PCG;
        preconditioner   DIC;
        tolerance        1e-06;
        relTol           0.1;
    }
}
I have everything in the google drive link.

I suspect my boundary condition and played with that a lot but didnt have any success and my solution divergences in the very first iteration

Code:
Create time

Create fluid mesh for region air_domain for time = 0

Create fluid mesh for region water_domain for time = 0

Create solid mesh for region solid_domain for time = 0

*** Reading fluid mesh thermophysical properties for region air_domain

    Adding to thermoFluid

Selecting thermodynamics package 
{
    type            heRhoThermo;
    mixture         pureMixture;
    transport       polynomial;
    thermo          hPolynomial;
    equationOfState icoPolynomial;
    specie          specie;
    energy          sensibleEnthalpy;
}

    Adding to rhoFluid

    Adding to UFluid

    Adding to phiFluid

    Adding to gFluid

    Adding to hRefFluid

    Adding to ghFluid

    Adding to ghfFluid

    Adding to turbulence

Selecting turbulence model type RAS
Selecting RAS turbulence model kEpsilon
kEpsilonCoeffs
{
    Cmu             0.09;
    C1              1.44;
    C2              1.92;
    C3              -0.33;
    sigmak          1;
    sigmaEps        1.3;
}

Radiation model not active: radiationProperties not found
Selecting radiationModel none
    Adding MRF

No MRF models present

    Adding fvOptions

No finite volume options present

*** Reading fluid mesh thermophysical properties for region water_domain

    Adding to thermoFluid

Selecting thermodynamics package 
{
    type            heRhoThermo;
    mixture         pureMixture;
    transport       const;
    thermo          hConst;
    equationOfState perfectFluid;
    specie          specie;
    energy          sensibleInternalEnergy;
}

    Adding to rhoFluid

    Adding to UFluid

    Adding to phiFluid

    Adding to gFluid

    Adding to hRefFluid

    Adding to ghFluid

    Adding to ghfFluid

    Adding to turbulence

Selecting turbulence model type laminar
Radiation model not active: radiationProperties not found
Selecting radiationModel none
    Adding MRF

No MRF models present

    Adding fvOptions

No finite volume options present

*** Reading solid mesh thermophysical properties for region solid_domain

    Adding to thermos

Selecting thermodynamics package 
{
    type            heSolidThermo;
    mixture         pureMixture;
    transport       constIso;
    thermo          hConst;
    equationOfState rhoConst;
    specie          specie;
    energy          sensibleEnthalpy;
}

    Adding to radiations

Radiation model not active: radiationProperties not found
Selecting radiationModel none
    Adding fvOptions

No finite volume options present

Time = 1


Solving for fluid region air_domain
DILUPBiCG:  Solving for Ux, Initial residual = 1, Final residual = 0.05257607, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 1, Final residual = 0.04018972, No Iterations 3
DILUPBiCG:  Solving for Uz, Initial residual = 1, Final residual = 0.05142399, No Iterations 2
DILUPBiCG:  Solving for h, Initial residual = 1, Final residual = 0.08905775, No Iterations 2
Min/max T:293.15 300.0003
GAMG:  Solving for p_rgh, Initial residual = 1, Final residual = 0.008710555, No Iterations 8
GAMG:  Solving for p_rgh, Initial residual = 0.08695835, Final residual = 0.0001994177, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 0.009356995, Final residual = 2.857887e-05, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 0.001269825, Final residual = 1.161426e-05, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 0.0003067193, Final residual = 1.221515e-06, No Iterations 3
GAMG:  Solving for p_rgh, Initial residual = 8.127729e-05, Final residual = 5.682916e-07, No Iterations 2
time step continuity errors : sum local = 0.001377804, global = 3.193082e-05, cumulative = 3.193082e-05
Min/max rho:1.170812 1.199585
DILUPBiCG:  Solving for epsilon, Initial residual = 0.2477916, Final residual = 0.02169919, No Iterations 2
bounding epsilon, min: -0.1537348 max: 74.9272 average: 9.377313
DILUPBiCG:  Solving for k, Initial residual = 1, Final residual = 0.07581812, No Iterations 3

Solving for fluid region water_domain
DILUPBiCG:  Solving for Ux, Initial residual = 1, Final residual = 0.02036105, No Iterations 17
DILUPBiCG:  Solving for Uy, Initial residual = 1, Final residual = 0.06697598, No Iterations 13
DILUPBiCG:  Solving for Uz, Initial residual = 1, Final residual = 0.06763109, No Iterations 11
DILUPBiCG:  Solving for e, Initial residual = 1, Final residual = 0.05426087, No Iterations 16
Min/max T:299.9414 353.15
GAMG:  Solving for p_rgh, Initial residual = 1, Final residual = 0.008721249, No Iterations 14
GAMG:  Solving for p_rgh, Initial residual = 0.8852784, Final residual = 0.003070489, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 0.05862079, Final residual = 0.0004594317, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 0.008742093, Final residual = 8.090802e-05, No Iterations 23
GAMG:  Solving for p_rgh, Initial residual = 0.01612499, Final residual = 6.594953e-05, No Iterations 3
GAMG:  Solving for p_rgh, Initial residual = 0.003798012, Final residual = 3.770664e-05, No Iterations 2
time step continuity errors : sum local = 0.003390077, global = -0.0003362716, cumulative = -0.0003043408
Min/max rho:2 2

Solving for solid region solid_domain
DICPCG:  Solving for h, Initial residual = 0.9999927, Final residual = 0.08746619, No Iterations 3
DICPCG:  Solving for h, Initial residual = 0.1366519, Final residual = 0.007957356, No Iterations 3
DICPCG:  Solving for h, Initial residual = 0.06695286, Final residual = 0.003200763, No Iterations 3
DICPCG:  Solving for h, Initial residual = 0.04195219, Final residual = 0.00191589, No Iterations 3
DICPCG:  Solving for h, Initial residual = 0.029766, Final residual = 0.002800009, No Iterations 2
DICPCG:  Solving for h, Initial residual = 0.02267911, Final residual = 0.001069138, No Iterations 3
Min/max T:300 300.0004
ExecutionTime = 104.02 s  ClockTime = 104 s

Time = 2


Solving for fluid region air_domain
DILUPBiCG:  Solving for Ux, Initial residual = 0.9242532, Final residual = 0.03203833, No Iterations 4
DILUPBiCG:  Solving for Uy, Initial residual = 0.9410005, Final residual = 0.03857488, No Iterations 4
DILUPBiCG:  Solving for Uz, Initial residual = 0.9284244, Final residual = 0.05554513, No Iterations 4
DILUPBiCG:  Solving for h, Initial residual = 0.9218401, Final residual = 0.08333141, No Iterations 3
Min/max T:-203.8075 498.9083
GAMG:  Solving for p_rgh, Initial residual = 0.4579909, Final residual = 0.002487677, No Iterations 5
As you can see my temperature in the air_domain explodes.

Any help will be highly appreciated.

Thanks again
Ali
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Old   March 30, 2016, 12:17
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Alex,

Any suggestions?
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Old   April 4, 2016, 12:03
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Hello everyone again,

Ok I haven't receive any hint from here but I'll keep updating maybe someone can eventually help me.

I did a lot of throuble shooting with my model and turns out my initial boundary condition werent completely right. Now, I'm facing another problem which I am not sure what is causing this problem.

The problem is, in my air domain, there is one voxel that blows up and the rest are fine as you can see in the image. And also the air doesn't get to the end of the domain and just stuck near close the inlet.

Any suggestions?


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File Type: png airDomain2.png (77.4 KB, 74 views)
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Old   June 16, 2016, 01:46
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would you please share the fvSchemes
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Old   June 17, 2016, 10:05
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Quote:
Originally Posted by nimasam View Post
would you please share the fvSchemes
Hi Nima,

Thanks for the response. Here are my fvSchemes files for
Air Domain:

Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
    default steadyState;
}

gradSchemes
{
    default         Gauss linear;
}

divSchemes
{
    default         none;

    div(phi,U)      bounded Gauss upwind;
    div(phi,K)      bounded Gauss upwind;
    div(phi,e)      bounded Gauss upwind;
    div(phi,Ekp)    bounded Gauss upwind;
    div(phi,h)      bounded Gauss upwind;
    div(phi,k)      bounded Gauss upwind;
    div(phi,epsilon) bounded Gauss upwind;
    div(phi,omega) bounded Gauss upwind;
    div(phi,R)      bounded Gauss upwind;
    div(R)          bounded Gauss upwind;
    div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
    default        Gauss linear corrected;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         corrected;
}

// ************************************************************************* //
Solid domain:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system/solid_domain";
    object      fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
    default     steadyState;
}

gradSchemes
{
    default         Gauss linear;
}

divSchemes
{
    default         none;
}

laplacianScsteadyStatehemes
{
    default             none;
    laplacian(alpha,h)  Gauss linear uncorrected;
}

laplacianSchemes
{
    default        Gauss linear corrected;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         uncorrected;
}


// ************************************************************************* //
And Water domain:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
    default steadyState;
}

gradSchemes
{
    default         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,e)      bounded Gauss upwind;
    div(phi,Ekp)    bounded Gauss upwind;
    div(phi,k)      bounded Gauss upwind;
    div(phi,omega) bounded Gauss upwind;
    div(phi,epsilon) bounded Gauss upwind;
    div(phi,R)      bounded Gauss upwind;
    div(R)          bounded Gauss linear;
    div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
    default        Gauss linear corrected;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         corrected;
}

// ************************************************************************* //
Thanks
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Old   June 18, 2016, 01:58
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1- change air fvScheme as:
Code:
gradSchemes
{
    default         cellLimited Gauss linear 0.5;
}
2-turn off turbulence, run several iterations in laminar then turn on turbulence
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