[yasasvi.harishkumar]

This is my blockMeshDict:

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 5 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 0.001;

vertices
(
(20 0 0)
(65 0 0)
(65 0.0065 0)
(20 0.0020 0)

(20 0 40)
(65 0 40)
(65 0.0065 40)
(20 0.0020 40)
);

edges
(
line 0 1
line 3 2
line 7 6
line 4 5

line 0 3 //(19.9992384613 0.17453071 0)
line 1 2 //(64.9975249992 0.5672248074 0)
line 5 6 //(64.9975249992 0.5672248074 40)
line 4 7 //(19.9992384613 0.17453071 40)

line 0 4
line 1 5
line 2 6
line 3 7
);

blocks
(
hex (1 0 4 5 2 3 7 6)
(18 1 18)
simpleGrading
(1 1 1)
);

boundary
(
inlet
{
type patch;
faces ((1 2 6 5));
}
outlet
{
type patch;
faces ((7 4 0 3));
}
bottom
{
type patch;
faces ((0 1 5 4));
}
top
{
type patch; //(or wall)
faces ((3 2 6 7));
}
wall
{
type wall;
faces (
(4 7 6 5)
(0 3 2 1)
);
}
);




I'm trying to extrude this mesh to make a cylinder with a hole in the middle. This is my extrudeMeshDict file:




/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.2.2 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object extrudeMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

constructFrom patch;

sourceCase ".";
sourcePatches (top);
exposedPatchName bottom;
flipNormals false;

extrudeModel sector;

nLayers 10;

expansionRatio 1.0; //0.9;

sectorCoeffs
{
axisPt (0 0 20);
axis (0 0 65);
angle 360;
}

mergeFaces true; //false;

mergeTol 0;


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




But when I run extrudeMesh and then run checkMesh, it gives me the following error:






Create time

Create polyMesh for time = 0

Time = 0

Mesh stats
points: 380
internal points: 0
faces: 730
internal faces: 350
cells: 180
faces per cell: 6
boundary patches: 5
point zones: 0
face zones: 1
cell zones: 0

Overall number of cells of each type:
hexahedra: 180
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
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: 1 (OK).

Checking patch topology for multiply connected surfaces...
Patch Faces Points Surface topology
inlet 10 20 ok (non-closed singly connected)
outlet 10 20 ok (non-closed singly connected)
bottom 0 0 ok (empty)
top 0 0 ok (empty)
wall 360 380 ok (non-closed singly connected)

Checking geometry...
Overall domain bounding box (-0.065 -4.0182158 -168960) (0.065 4.0182158 0.04)
Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
Mesh has 3 solution (non-empty) directions (1 1 1)
Boundary openness (4.2747924e-17 1.5629954e-19 5.0680011e-24) OK.
***High aspect ratio cells found, Max aspect ratio: 3984422.4, number of cells 180
<<Writing 180 cells with high aspect ratio to set highAspectRatioCells
Minimum face area = 0.0001. Maximum face area = 8069.1202. Face area magnitudes OK.
Min volume = 0.032828302. Max volume = 1.9596511. Total volume = 123.48904. Cell volumes OK.
Mesh non-orthogonality Max: 89.999984 average: 77.614853
*Number of severely non-orthogonal (> 70 degrees) faces: 280.
Non-orthogonality check OK.
<<Writing 280 non-orthogonal faces to set nonOrthoFaces
Face pyramids OK.
***Max skewness = 49592.18, 36 highly skew faces detected which may impair the quality of the results
<<Writing 36 skew faces to set skewFaces
Coupled point location match (average 0) OK.

Failed 2 mesh checks.

Time = 0.0001

Mesh stats
points: 418
internal points: 0
faces: 748
internal faces: 332
cells: 180
faces per cell: 6
boundary patches: 5
point zones: 0
face zones: 0
cell zones: 0

Overall number of cells of each type:
hexahedra: 180
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
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: 1 (OK).

Checking patch topology for multiply connected surfaces...
Patch Faces Points Surface topology
inlet 10 22 ok (non-closed singly connected)
outlet 10 22 ok (non-closed singly connected)
bottom 0 0 ok (empty)
top 36 76 ok (non-closed singly connected)
wall 360 418 ok (non-closed singly connected)

Checking geometry...
Overall domain bounding box (-0.065 -4.0182158 -168960) (0.065 4.0182158 0.04)
Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
Mesh has 3 solution (non-empty) directions (1 1 1)
Boundary openness (4.1067703e-17 -1.1295084e-18 -2.6830594e-23) OK.
***High aspect ratio cells found, Max aspect ratio: 4150387, number of cells 180
<<Writing 180 cells with high aspect ratio to set highAspectRatioCells
Minimum face area = 3.202096e-05. Maximum face area = 10893.312. Face area magnitudes OK.
Min volume = 0.010091589. Max volume = 2.2678961. Total volume = 123.48904. Cell volumes OK.
Mesh non-orthogonality Max: 89.999985 average: 80.104291
*Number of severely non-orthogonal (> 70 degrees) faces: 280.
Non-orthogonality check OK.
<<Writing 280 non-orthogonal faces to set nonOrthoFaces
Face pyramids OK.
***Max skewness = 51694.863, 54 highly skew faces detected which may impair the quality of the results
<<Writing 54 skew faces to set skewFaces
Coupled point location match (average 0) OK.

Failed 2 mesh checks.

End


Can someone please explain the problem here and give me solution to reduce the skewness and aspect ratio. Thank you.