CFD Online Discussion Forums - [blockMesh] 4 inlets to 1 outlet and potential internal faces

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- - [blockMesh] 4 inlets to 1 outlet and potential internal faces (https://www.cfd-online.com/Forums/openfoam-meshing/114889-4-inlets-1-outlet-potential-internal-faces.html)

4 inlets to 1 outlet and potential internal faces

Alright, I am a complete OpenFOAM newbie, been working on it for less than a month and I've been thrown in the deep end already. I know how to do the basics: working with the blockMeshDict file to create my geometry, using blockMesh to create my mesh, and using icoFoam to run it all. However, I'm being pushed for results and have hit a snag that I can't seem to beat.

What I'm trying to do is create a duct that is split both vertically and horizontally. Currently modeling it as 4 inlets and 4 ducts running next to each other for the first stage. The problem comes in the end section where I am trying to mix the flow into a single outlet. I am receiving an error with the solver icoFoam, that looks something like this:

"--> FOAM FATAL ERROR:
This mesh contains patches of type empty but is not 1D or 2D
by virtue of the fact that the number of faces of this
empty patch is not divisible by the number of cells.

From function emptyFvPatchField<Type>::updateCoeffs()
in file fields/fvPatchFields/constraint/empty/emptyFvPatchField.C at line 150."

I'm not really sure how I'm supposed to go about creating this. I've tried with 0-thickness walls, but that just opens up a whole new set of problems. Any kind of help would be appreciated.

Code is kinda giant:

Code:

/*--------------------------------*- C++ -*----------------------------------*\

| =========                 |                                                 |

| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |

|  \\    /   O peration     | Version:  1.7.1                                 |

|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |

|    \\/     M anipulation  |                                                 |

\*---------------------------------------------------------------------------*/

FoamFile

{

    version     2.0;

    format      ascii;

    class       dictionary;

    object      blockMeshDict;

}

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



convertToMeters 1;



vertices        

(



(    0.000    0.000    0.000    )    //    0

(    0.127    0.000    0.000    )    //    1

(    4.628    1.206    0.000    )    //    2

(    4.848    1.333    0.000    )    //    3

(    7.885    2.147    0.000    )    //    4

(    10.323    2.147    0.000    )    //    5

(    0.000    2.896    0.000    )    //    6

(    0.127    2.896    0.000    )    //    7

(    3.164    3.710    0.000    )    //    8

(    3.384    3.837    0.000    )    //    9

(    7.885    5.043    0.000    )    //    10

(    10.323    5.043    0.000    )    //    11

(    0.000    0.000    2.896    )    //    12

(    0.127    0.000    2.896    )    //    13

(    4.628    1.206    2.896    )    //    14

(    4.848    1.333    2.896    )    //    15

(    7.885    2.147    2.896    )    //    16

(    10.323    2.147    2.896    )    //    17

(    0.000    2.896    2.896    )    //    18

(    0.127    2.896    2.896    )    //    19

(    3.164    3.710    2.896    )    //    20

(    3.384    3.837    2.896    )    //    21

(    7.885    5.043    2.896    )    //    22

(    10.323    5.043    2.896    )    //    23

(    0.000    1.443    0.000    )    //    24

(    0.127    1.443    0.000    )    //    25

(    3.896    2.453    0.000    )    //    26

(    4.116    2.580    0.000    )    //    27

(    7.885    3.590    0.000    )    //    28

(    10.323    3.590    0.000    )    //    29

(    0.000    1.443    1.443    )    //    30

(    0.127    1.443    1.443    )    //    31

(    3.896    2.453    1.443    )    //    32

(    4.116    2.580    1.443    )    //    33

(    7.885    3.590    1.443    )    //    34

(    10.323    3.590    1.443    )    //    35

(    0.000    1.453    2.896    )    //    36

(    0.127    1.453    2.896    )    //    37

(    3.896    2.463    2.896    )    //    38

(    4.116    2.590    2.896    )    //    39

(    7.885    3.600    2.896    )    //    40

(    10.323    3.600    2.896    )    //    41

(    0.000    0.000    1.443    )    //    42

(    0.127    0.000    1.443    )    //    43

(    4.628    1.206    1.443    )    //    44

(    4.848    1.333    1.443    )    //    45

(    7.885    2.147    1.443    )    //    46

(    10.323    2.147    1.443    )    //    47

(    0.000    2.896    1.453    )    //    48

(    0.127    2.896    1.453    )    //    49

(    3.164    3.710    1.453    )    //    50

(    3.384    3.837    1.453    )    //    51

(    7.885    5.043    1.453    )    //    52

(    10.323    5.043    1.453    )    //    53

(    0.000    0.000    1.453    )    //    54

(    0.127    0.000    1.453    )    //    55

(    4.628    1.206    1.453    )    //    56

(    4.848    1.333    1.453    )    //    57

(    7.885    2.147    1.453    )    //    58

(    10.323    2.147    1.453    )    //    59

(    0.000    1.443    1.453    )    //    60

(    0.127    1.443    1.453    )    //    61

(    3.896    2.453    1.453    )    //    62

(    4.116    2.580    1.453    )    //    63

(    7.885    3.590    1.453    )    //    64

(    10.323    3.590    1.453    )    //    65

(    0.000    1.443    2.896    )    //    66

(    0.127    1.443    2.896    )    //    67

(    3.896    2.453    2.896    )    //    68

(    4.116    2.580    2.896    )    //    69

(    7.885    3.590    2.896    )    //    70

(    10.323    3.590    2.896    )    //    71

(    0.000    1.453    0.000    )    //    72

(    0.127    1.453    0.000    )    //    73

(    3.896    2.463    0.000    )    //    74

(    4.116    2.590    0.000    )    //    75

(    7.885    3.600    0.000    )    //    76

(    10.323    3.600    0.000    )    //    77

(    0.000    1.453    1.443    )    //    78

(    0.127    1.453    1.443    )    //    79

(    3.896    2.463    1.443    )    //    80

(    4.116    2.590    1.443    )    //    81

(    7.885    3.600    1.443    )    //    82

(    10.323    3.600    1.443    )    //    83

(    0.000    2.896    1.443    )    //    84

(    0.127    2.896    1.443    )    //    85

(    3.164    3.710    1.443    )    //    86

(    3.384    3.837    1.443    )    //    87

(    7.885    5.043    1.443    )    //    88

(    10.323    5.043    1.443    )    //    89

(    0.000    1.453    1.453    )    //    90

(    0.127    1.453    1.453    )    //    91

(    3.896    2.463    1.453    )    //    92

(    4.116    2.590    1.453    )    //    93

(    7.885    3.600    1.453    )    //    94

(    10.323    3.600    1.453    )    //    95

(    13.323    2.147    0.000    )    //    96

(    13.323    5.043    0.000    )    //    97

(    13.323    5.043    2.896    )    //    98

(    13.323    2.147    2.896    )    //    99







);



blocks          

(

    hex (0 1 25 24 42 43 31 30) (1 10 10) simpleGrading (1 1 1)

    hex (1 2 26 25 43 44 32 31) (14 10 10) simpleGrading (1 1 1)

    hex (2 3 27 26 44 45 33 32) (1 10 10) simpleGrading (1 1 1)

    hex (3 4 28 27 45 46 34 33) (14 10 10) simpleGrading (1 1 1)

    hex (4 5 29 28 46 47 35 34) (10 10 10) simpleGrading (1 1 1)



    hex (54 55 61 60 12 13 67 66) (1 10 10) simpleGrading (1 1 1)

    hex (55 56 62 61 13 14 68 67) (14 10 10) simpleGrading (1 1 1)

    hex (56 57 63 62 14 15 69 68) (1 10 10) simpleGrading (1 1 1)

    hex (57 58 64 63 15 16 70 69) (14 10 10) simpleGrading (1 1 1)

    hex (58 59 65 64 16 17 71 70) (10 10 10) simpleGrading (1 1 1)



    hex (72 73 7 6 78 79 85 84) (1 10 10) simpleGrading (1 1 1)

    hex (73 74 8 7 79 80 86 85) (14 10 10) simpleGrading (1 1 1)

    hex (74 75 9 8 80 81 87 86) (1 10 10) simpleGrading (1 1 1)

    hex (75 76 10 9 81 82 88 87) (14 10 10) simpleGrading (1 1 1)

    hex (76 77 11 10 82 83 89 88) (10 10 10) simpleGrading (1 1 1)



    hex (90 91 49 48 36 37 19 18) (1 10 10) simpleGrading (1 1 1)

    hex (91 92 50 49 37 38 20 19) (14 10 10) simpleGrading (1 1 1)

    hex (92 93 51 50 38 39 21 20) (1 10 10) simpleGrading (1 1 1)

    hex (93 94 52 51 39 40 22 21) (14 10 10) simpleGrading (1 1 1)

    hex (94 95 53 52 40 41 23 22) (10 10 10) simpleGrading (1 1 1)



    hex (5 96 97 11 17 99 98 23) (10 10 10) simpleGrading (1 1 1)

);



edges           

(

    arc 1 2 (2.43 0.303 0)

    arc 43 44 (2.43 0.303 1.443)

    arc 55 56 (2.43 0.303 1.453)

    arc 13 14 (2.43 0.303 2.896)

    arc 3 4 (6.331 1.942 0)

    arc 45 46 (6.331 1.942 1.443)

    arc 57 58 (6.331 1.942 1.453)

    arc 15 16 (6.331 1.942 2.896)



    arc 7 8 (1.681 3.101 0)

    arc 85 86 (1.681 3.101 1.443)

    arc 49 50 (1.681 3.101 1.453)

    arc 19 20 (1.681 3.101 2.896)

    arc 9 10 (5.582 4.74 0)

    arc 87 88 (5.582 4.74 1.443)

    arc 51 52 (5.582 4.74 1.453)

    arc 21 22 (5.582 4.74 2.896)



    arc 25 26 (2.0555 1.697 0)

    arc 31 32 (2.0555 1.697 1.443)

    arc 61 62 (2.0555 1.697 1.453)

    arc 67 68 (2.0555 1.697 2.896)

    arc 27 28 (5.9565 3.336 0)

    arc 33 34 (5.9565 3.336 1.443)

    arc 63 64 (5.9565 3.336 1.453)

    arc 69 70 (5.9565 3.336 2.896)



    arc 73 74 (2.0555 1.707 0)

    arc 79 80 (2.0555 1.707 1.443)

    arc 91 92 (2.0555 1.707 1.453)

    arc 37 38 (2.0555 1.707 2.896)

    arc 75 76 (5.9565 3.346 0)

    arc 81 82 (5.9565 3.346 1.443)

    arc 93 94 (5.9565 3.346 1.453)

    arc 39 40 (5.9565 3.346 2.896)

);



patches           

(

);





patches         

(

    patch inlet1

    (

        (0 42 30 24)

    )

    patch inlet2

    (

        (12 54 60 66)

    )

    patch inlet3

    (

        (48 18 36 90)

    )

    patch inlet4

    (

        (6 84 78 72)

    )

    patch outlet

    (

        (96 97 98 99)

    )

//    patch outlet1

//    (

//        (5 47 35 29)

//    )

//    patch outlet2

//    (

//        (17 59 65 71)

//    )

//    patch outlet3

//    (

//        (53 23 41 95)

//    )

//    patch outlet4

//    (

//        (11 89 83 77)

//    )

    wall sides

    (



        (0 42 43 1)

        (1 43 44 2)

        (2 44 45 3)

        (3 45 46 4)

        (4 46 47 5)



        (42 43 31 30)

        (43 44 32 31)

        (44 45 33 32)

        (45 46 34 33)

        (46 47 35 34)



        (25 24 30 31)

        (26 25 31 32)

        (27 26 32 33)

        (28 27 33 34)

        (29 28 34 35)



        (25 24 0 1)

        (26 25 1 2)

        (27 26 2 3)

        (28 27 3 4)

        (29 28 4 5)



(    54    55    61    60    )

(    55    56    62    61    )

(    56    57    63    62    )

(    57    58    64    63    )

(    58    59    65    64    )



(    54    55    13    12    )

(    55    56    14    13    )

(    56    57    15    14    )

(    57    58    16    15    )

(    58    59    17    16    )



(    66    67    13    12    )

(    67    68    14    13    )

(    68    69    15    14    )

(    69    70    16    15    )

(    70    71    17    16    )



(    66    67    61    60    )

(    67    68    62    61    )

(    68    69    63    62    )

(    69    70    64    63    )

(    70    71    65    64    )



        (36 37 19 18)

        (37 38 20 19)

        (38 39 21 20)

        (39 40 22 21)

        (40 41 23 22)



        (49 48 18 19)

        (50 49 19 20)

        (51 50 20 21)

        (52 51 21 22)

        (53 52 22 23)



(    48    49    91    90    )

(    49    50    92    91    )

(    50    51    93    92    )

(    51    52    94    93    )

(    52    53    95    94    )



(    36    37    91    90    )

(    37    38    92    91    )

(    38    39    93    92    )

(    39    40    94    93    )

(    40    41    95    94    )



(    72    73    7    6    )

(    73    74    8    7    )

(    74    75    9    8    )

(    75    76    10    9    )

(    76    77    11    10    )



(    72    73    79    78    )

(    73    74    80    79    )

(    74    75    81    80    )

(    75    76    82    81    )

(    76    77    83    82    )



(    84    85    79    78    )

(    85    86    80    79    )

(    86    87    81    80    )

(    87    88    82    81    )

(    88    89    83    82    )



(    84    85    7    6    )

(    85    86    8    7    )

(    86    87    9    8    )

(    87    88    10    9    )

(    88    89    11    10    )



    (5 96 97 11)

    (11 97 98 23)

    (23 98 99 17)

    (17 99 96 5)





    )

);



mergePatchPairs 

(

);



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

Hi,
I suspect one of the patches in a parameter file (either P or U) in the 0 folder has the type "empty". Seeing this is a 3D case, you would want to change the type to something else - most likely to a fixedValue or zeroGradient. Copy paste the U and P files so I can see what you have defined each patch as.

Luke

Some general advice I can give you, I'm a new user too!

Always run checkMesh before running your case.

Code:

checkMesh

In your case, there are too many errors and the terminal cannot display everything. So I run this:

Code:

checkMesh > log &

The process will run in the background and the results will be stored in a file called 'log'.

Seeing the log, here's the log

Code:

/*---------------------------------------------------------------------------*\

| =========                 |                                                 |

| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |

|  \\    /   O peration     | Version:  2.1.1                                 |

|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |

|    \\/     M anipulation  |                                                 |

\*---------------------------------------------------------------------------*/

Build  : 2.1.1-221db2718bbb

Exec   : checkMesh

Date   : Mar 20 2013

Time   : 16:08:31

Host   : "p150"

PID    : 4108

Case   : /home/abdulhaq/Documents/Random/OF/block

nProcs : 1

sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).

fileModificationChecking : Monitoring run-time modified files using timeStampMaster

allowSystemOperations : Disallowing user-supplied system call operations



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

Create time



Create polyMesh for time = 0



Time = 0



Mesh stats

    points:           21175

    faces:            54900

    internal faces:   47100

    cells:            17000

    boundary patches: 7

    point zones:      0

    face zones:       0

    cell zones:       0



Overall number of cells of each type:

    hexahedra:     17000

    prisms:        0

    wedges:        0

    pyramids:      0

    tet wedges:    0

    tetrahedra:    0

    polyhedra:     0



Checking topology...

    Boundary definition OK.

 ***Total number of faces on empty patches is not divisible by the number of cells in the mesh. Hence this mesh is not 1D or 2D.

    Cell to face addressing OK.

    Point usage OK.

    Upper triangular ordering OK.

    Face vertices OK.

   *Number of regions: 5

    The mesh has multiple regions which are not connected by any face.

  <<Writing region information to "0/cellToRegion"



Checking patch topology for multiply connected surfaces ...

    Patch               Faces    Points   Surface topology                  

    inlet1              100      121      ok (non-closed singly connected)  

    inlet2              100      121      ok (non-closed singly connected)  

    inlet3              100      121      ok (non-closed singly connected)  

    inlet4              100      121      ok (non-closed singly connected)  

    outlet              100      121      ok (non-closed singly connected)  

    sides               6800     7000     ok (non-closed singly connected)  

    defaultFaces        500      605      ok (non-closed singly connected)  



Checking geometry...

    Overall domain bounding box (0 0 0) (13.323 5.043 2.896)

    Mesh (non-empty, non-wedge) directions (0 1 1)

    Mesh (non-empty) directions (0 1 1)

 ***Number of edges not aligned with or perpendicular to non-empty directions: 26356

  <<Writing 14520 points on non-aligned edges to set nonAlignedEdges

    Boundary openness (7.55685e-17 -1.12341e-16 -4.85609e-17) OK.

    Max cell openness = 2.38624e-16 OK.

    Max aspect ratio = 1.18276 OK.

    Minumum face area = 0.0183261. Maximum face area = 0.08688.  Face area magnitudes OK.

    Min volume = 0.00264446. Max volume = 0.0251604.  Total volume = 114.395.  Cell volumes OK.

    Mesh non-orthogonality Max: 1.07006 average: 0.256515

    Non-orthogonality check OK.

    Face pyramids OK.

    Max skewness = 0.0400646 OK.

    Coupled point location match (average 0) OK.



Failed 1 mesh checks.



End

blockMesh is cool but the moment the geometry gets complex, you will either have to use another mesh generator OR use something that would export geometry to blockMesh format such as this

Edit: I wonder what OF version are you using, the header files of your blockMeshDict says 1.7.1 while the FoamFile dict says 2.0, so you may not be seeing the same results from checkMesh if you're using an older version.

Thanks for the suggestions.

So what I ended up doing was reducing my inner walls down to 0 thickness for the 4-duct section. When they converge at the end, I made the nozzle with another 2x2 geometry, but defined the the area that used to be 'inner walls' as patches instead of walls. There are 8 of them that form a + shape that just got labeled inner1-inner8. Then I assigned their 0/p and 0/U values as uniform 0 and zeroGradient, respectively (the same as an outlet when I was getting the damn thing to work.)

There are a few quirks, but the geometry does what I want it to do for the most part.

Now comes the question: how the hell do I get my Courant Number to not crash? It's skyrocketing off the charts and crashing my solver at about 0.14 s out of a 1 s simulation. :/

Help?

Thanks in advance!

Don't use icoFoam, use pimpleFoam or pisoFoam.

Btw, I edited the results from checkMesh, the previous errors were something to do with my setup.

This is what fails now:

Code:

    The mesh has multiple regions which are not connected by any face.

  <<Writing region information to "0/cellToRegion"

So how does one acquire/use those solvers? Again, super-newbie, so sorry for the dumb questions.

Those solvers come installed with the standard OpenFOAM distribution. It should be just a matter of typing simpleFoam instead of icoFoam, although you may need to add more fields.

Quote:

Originally Posted by mturcios777 (Post 415340)

Those solvers come installed with the standard OpenFOAM distribution. It should be just a matter of typing simpleFoam instead of icoFoam, although you may need to add more fields.

Typed simpleFoam instead of ico and got this error:

Code:

--> FOAM FATAL IO ERROR: 

keyword SIMPLE is undefined in dictionary "/home/user/OpenFOAM/user-1.7.x/run/DuctDesign/80/80PctFullNozzle/system/fvSolution"



file: /home/user/OpenFOAM/user-1.7.x/run/DuctDesign/80/80PctFullNozzle/system/fvSolution from line 22 to line 42.



    From function dictionary::subDict(const word& keyword) const

    in file db/dictionary/dictionary.C at line 456.



FOAM exiting

What do?

Before using any solver, I suggest copying all the files from a case with the same solver (especially the files in the system folder), then start adjusting it to your needs.

To obtain these files, browse to the OpenFOAM installation directory and go to the tutorials folder, there you will find sample cases for each solver. Or you can type tut in the terminal and it will take you there.

Back to your error, it is telling you that something is undefined in your fvSolution dictionary. If you check the sample cases for the simpleFoam solver, you'll find all the cases have the following in the fvSolution:

Code:

SIMPLE

{

    nNonOrthogonalCorrectors 0;



    residualControl

    {

        p               1e-2;

        U               1e-3;

        "(k|epsilon|omega)" 1e-3;

    }

}

Above taken from: /tutorials/incompressible/simpleFoam/pitzDaily

Or this

Code:

SIMPLE

{

    nNonOrthogonalCorrectors 0;

}

Taken from: /tutorials/incompressible/simpleFoam/motorBike

The reason I told you to copy cases then adjust to your needs is to avoid errors such as the one you have. Other errors will appear as well, for example; simpleFoam is a steady state solver while icoFoam is unsteady so another thing that you need to change is the scheme used for the time derivative (system/fvSchemes). For simpleFoam it should be:

Code:

ddtSchemes

{

    default         steadyState;

}

Another obvious one is to change the solver in the controlDict:

Code:

application simpleFoam;

Copying the system folder is the way to go when changing solvers :)

Edit: I also suggest upgrading your OpenFOAM version unless you have a special reason for using 1.7

Quote:

Originally Posted by ElsaStegosaurus (Post 415265)

Dear ElsaStegosaurus,
I saw your post, sorry for writing to you but I am desperate and hope you can help me. I am using OF 2.1.1. I am trying to use blockmesh to get injector inside combustion chamber(cylinder) as you can see in the picture. the problem is defining the internal wall for the injector surface, I do not have thickness for it, I defined it as walls but I got this error :

--> FOAM FATAL ERROR:
Trying to specify a boundary face 4(19 18 22 23) on the face on cell 5 which is either an internal face or already belongs to some other patch. This is face 0 of patch 3 named innerWalls.

From function polyMesh::setTopology
(
const cellShapeList& cellsAsShapes,
const faceListList& boundaryFaces,
const wordList& boundaryPatchNames,
labelList& patchSizes,
labelList& patchStarts,
label& defaultPatchStart,
label& nFaces,
cellList& cells
)
in file meshes/polyMesh/polyMeshFromShapeMesh.C at line 360.

FOAM aborting

Then I tried to do define inner walls' as patches instead of walls as you did but i did not work neither. Please could you help me, any advice or thought would be helpful.
Sandy,

Quote:

Originally Posted by sandy13 (Post 428010)

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