[KokuraCloud]

Hello everyone,

I've been trying to decompose my 2-D Mesh using scotch.
Unfortunately every cell gets distributed to the same processor 0.
The remaining 3 processors wont get any cells.

Did this happen to anyone else? I'd appreciate any kind of help.

- Mirko

Calculating distribution of cells
Selecting decompositionMethod scotch

Finished decomposition in 0.01 s

Calculating original mesh data

Distributing cells to processors

Distributing faces to processors

Distributing points to processors

Constructing processor meshes

Processor 0
    Number of cells = 14400
    Number of processor patches = 0
    Number of processor faces = 0
    Number of boundary faces = 29820

Processor 1
    Number of cells = 0
    Number of processor patches = 0
    Number of processor faces = 0
    Number of boundary faces = 0

Processor 2
    Number of cells = 0
    Number of processor patches = 0
    Number of processor faces = 0
    Number of boundary faces = 0

Processor 3
    Number of cells = 0
    Number of processor patches = 0
    Number of processor faces = 0
    Number of boundary faces = 0

Number of processor faces = 0
Max number of cells = 14400 (300% above average 3600)
Max number of processor patches = 0 (-100% above average 1)
Max number of faces between processors = 0 (-100% above average 1)

Time = 0

Processor 0: field transfer
Processor 1: field transfer
--> FOAM Warning :
    From function Foam::polyMesh::polyMesh(const Foam::IOobject&)
    in file meshes/polyMesh/polyMesh.C at line 330
    no points in mesh
--> FOAM Warning :
    From function Foam::polyMesh::polyMesh(const Foam::IOobject&)
    in file meshes/polyMesh/polyMesh.C at line 335
    no cells in mesh
Processor 2: field transfer
--> FOAM Warning :
    From function Foam::polyMesh::polyMesh(const Foam::IOobject&)
    in file meshes/polyMesh/polyMesh.C at line 330
    no points in mesh
--> FOAM Warning :
    From function Foam::polyMesh::polyMesh(const Foam::IOobject&)
    in file meshes/polyMesh/polyMesh.C at line 335
    no cells in mesh
Processor 3: field transfer
--> FOAM Warning :
    From function Foam::polyMesh::polyMesh(const Foam::IOobject&)
    in file meshes/polyMesh/polyMesh.C at line 330
    no points in mesh
--> FOAM Warning :
    From function Foam::polyMesh::polyMesh(const Foam::IOobject&)
    in file meshes/polyMesh/polyMesh.C at line 335
    no cells in mesh

numberOfSubdomains 4;

method         scotch;

scotchCoeffs
{
   processorWeights
   (
       1
       1
       1
       1
   );

}

manualCoeffs
{
    dataFile    "cellDist";
}

simpleCoeffs
{
    n           (2 2 1);
    delta    0.001;
}

distributed     no;

roots           ( );

[louisgag]

Hi,
I assume you didn't get a reply because there is not enough information to see an "error" in your input files... Did you solve it? Otherwise you may want to share your full decomposeParDict...

[agustinvo]

Hi,


I found the same error in OpenFOAM-7.


This is my decomposeParDict:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.3.0                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      decomposeParDict;
}

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

numberOfSubdomains 4;

method          scotch;

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

Decomposing mesh region0

Create mesh

Calculating distribution of cells
 Foam::decompositionMethod::New 
{
    numberOfSubdomains 4;
    method          scotch;
}

Selecting decompositionMethod scotch

Finished decomposition in 0.1 s

Calculating original mesh data

Distributing cells to processors

Distributing faces to processors

Distributing points to processors

Constructing processor meshes

Processor 0
    Number of cells = 147456
    Number of processor patches = 0
    Number of processor faces = 0
    Number of boundary faces = 297248

Processor 1
    Number of cells = 0
    Number of processor patches = 0
    Number of processor faces = 0
    Number of boundary faces = 0

Processor 2
    Number of cells = 0
    Number of processor patches = 0
    Number of processor faces = 0
    Number of boundary faces = 0

Processor 3
    Number of cells = 0
    Number of processor patches = 0
    Number of processor faces = 0
    Number of boundary faces = 0

Number of processor faces = 0
Max number of cells = 147456 (300% above average 36864)
Max number of processor patches = 0 (-100% above average 1)
Max number of faces between processors = 0 (-100% above average 1)

Time = 0

Processor 0: field transfer
Processor 1: field transfer
--> FOAM Warning : 
    From function Foam::polyMesh::polyMesh(const Foam::IOobject&)
    in file meshes/polyMesh/polyMesh.C at line 332
    no points in mesh
--> FOAM Warning : 
    From function Foam::polyMesh::polyMesh(const Foam::IOobject&)
    in file meshes/polyMesh/polyMesh.C at line 337
    no cells in mesh
Processor 2: field transfer
--> FOAM Warning : 
    From function Foam::polyMesh::polyMesh(const Foam::IOobject&)
    in file meshes/polyMesh/polyMesh.C at line 332
    no points in mesh
--> FOAM Warning : 
    From function Foam::polyMesh::polyMesh(const Foam::IOobject&)
    in file meshes/polyMesh/polyMesh.C at line 337
    no cells in mesh
Processor 3: field transfer
--> FOAM Warning : 
    From function Foam::polyMesh::polyMesh(const Foam::IOobject&)
    in file meshes/polyMesh/polyMesh.C at line 332
    no points in mesh
--> FOAM Warning : 
    From function Foam::polyMesh::polyMesh(const Foam::IOobject&)
    in file meshes/polyMesh/polyMesh.C at line 337
    no cells in mesh

End

Have you found any solution?

[joshmccraney]

Here's what my decomposeParDict looks like for 16 cores and it runs fine:

numberOfSubdomains 16;

method          scotch;

simpleCoeffs
{
    n               ( 4 4 1 );
    delta           0.001;
}

hierarchicalCoeffs
{
    n               ( 1 1 1 );
    delta           0.001;
    order           xyz;
}

scotchCoeffs
{
    processorWeights ( 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 );
}

metisCoeffs
{
    processorWeights ( 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 );
}

manualCoeffs
{
    dataFile        "";
}

distributed     no;

roots           ( );

[SonnyD]

Hi guys, did you solve that issue? I'm getting the same errors in my decomposition. Never had that before while I used the ESI-Versions (v1906, v1912, v2006) of OF. Now that I changed to the foundation version (v7) I get this error:

"Processor 47: field transfer
--> FOAM Warning :
From function Foam:olyMesh:olyMesh(const Foam::IOobject&)
in file meshes/polyMesh/polyMesh.C at line 332
no points in mesh"


...for multiple processors in my decomposePar-log.
I checked my whole geometry many times, but I couldn't see anything getting wrong.
Does anyone have any suggestions or already solved that issue?


I just used method simple for decomposition of a 2D-mesh on 48 cores with simpleCoeffs: n (4 12 1) and delta 0.001.

[louisgag]

I've seen errors happen for simple/hierarchical if you have much more cells in the center of your domain as on the edges, but I haven't identified the source of the more general 0 cells problem. You can try the tips of Mark Olesen: parallel decomposition method in openfoam

[SonnyD]

Hello Louis,


thanks for your fast reply!
I think i just managed this issue. Somehow the cht-Solver of the foundation-version has a problem by using simple method. I just needed to change to hierarchial, which is almost the same. I couldn't imagine before, that simple method was the problem, because it is the most common used and easiest method.

Well.. changing versions is not that trivial anymore it seems .


But thank you again for your advice .