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[blockMesh] blockMesh error - Negative Volume Block

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Old   March 19, 2016, 11:35
Default blockMesh error - Negative Volume Block
  #1
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Mateus Peixoto
Join Date: Dec 2014
Posts: 11
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Hi all,
I'm pretty new at OpenFoam.

I want the pitzDaily case but with another geometry.
When I run blockMesh I got this error:


/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / 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 : blockMesh
Date : Mar 19 2016
Time : 11:30:15
Host : "mateus-HP-G42-Notebook-PC"
PID : 9692
Case : /home/mateus/Desktop/pitzDaily
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

Creating block mesh from
"/home/mateus/Desktop/pitzDaily/constant/polyMesh/blockMeshDict"
Creating curved edges
Creating topology blocks
Creating topology patches

Creating block mesh topology
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.133333 for face 0
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.133333 for face 1
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.133333 for face 2
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.133333 for face 3
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.133333 for face 4
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.133333 for face 5
--> FOAM Warning :
From function blockMesh::createTopology(IOdictionary&)
in file blockMesh/blockMeshTopology.C at line 255
negative volume block : 0, probably defined inside-out
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.666667 for face 0
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.666667 for face 1
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.666667 for face 2
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.666667 for face 3
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.666667 for face 4
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.666667 for face 5
--> FOAM Warning :
From function blockMesh::createTopology(IOdictionary&)
in file blockMesh/blockMeshTopology.C at line 255
negative volume block : 1, probably defined inside-out
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.666667 for face 0
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.666667 for face 1
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.666667 for face 2
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.666667 for face 3
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.666667 for face 4
--> FOAM Warning :
From function cellModel::mag(const labelList&, const pointField&)
in file meshes/meshShapes/cellModel/cellModel.C at line 128
zero or negative pyramid volume: -0.666667 for face 5
--> FOAM Warning :
From function blockMesh::createTopology(IOdictionary&)
in file blockMesh/blockMeshTopology.C at line 255
negative volume block : 2, probably defined inside-out

Check topology

Basic statistics
Number of internal faces : 2
Number of boundary faces : 14
Number of defined boundary faces : 14
Number of undefined boundary faces : 0
Checking patch -> block consistency

Creating block offsets
Creating merge list .

Creating polyMesh from blockMesh
Creating patches
Creating cells
Creating points with scale 0.001

Writing polyMesh
----------------
Mesh Information
----------------
boundingBox: (0 0 -0.0001) (0.012 0.004 0.0001)
nPoints: 65062
nCells: 32000
nFaces: 128530
nInternalFaces: 63470
----------------
Patches
----------------
patch 0 (start: 63470 size: 40) name: inlet
patch 1 (start: 63510 size: 80) name: outlet
patch 2 (start: 63590 size: 450) name: upperWall
patch 3 (start: 64040 size: 490) name: lowerWall
patch 4 (start: 64530 size: 64000) name: frontAndBack

End
Attached Files
File Type: txt blockMeshDict.txt (2.1 KB, 19 views)
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Old   March 20, 2016, 09:26
Default
  #2
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Hi,

Since blockMesh says there are negative volumes, the most probable reason is the way in which you have defined your vertices and the block made up of these vertices.

http://cfd.direct/openfoam/user-guide/blockMesh/

The link gives you the description on how to create the blockMesh.

In the case of a simple cube, I define the vertices of the lower square first before the upper square. For each of the squares, I start from the lower left, move in a anti-clockwise manner to the upper left.

Eg:
//Lower square
(0 0 0)
(0 1 0)
(1 1 0)
(1 0 0)

//Upper square
(0 0 1)
(0 1 1)
(1 1 1)
(1 0 1)

hex (0 1 2 3 4 5 6 7) ...

Hope this helps.

Cheers,
Antimony
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Old   June 22, 2016, 11:44
Red face
  #3
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Mojtaba
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i think its because of your chosen axis, they may be different from axis that are defined on openFoam.
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