# [Gmsh] non-orthogonal mesh problem

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December 19, 2017, 14:50
non-orthogonal mesh problem
#1
New Member

Luca Montagliani
Join Date: Nov 2017
Posts: 5
Rep Power: 8
Hi guys,
I have to build a mesh around an airfoil with gmsh and then run a simulation with OpenFOAM (v5).
Once the mesh is built and imported into OpenFOAM, I run checkMesh to verify that everything is OK, but it turns out that no-orthogonality is not respected.

The log is:
----------------------------------------------------------------------------------
Create time

Create mesh for time = 0

Time = 0

Mesh stats
points: 454960
internal points: 0
faces: 906818
internal faces: 451858
cells: 226446
faces per cell: 6
boundary patches: 4
point zones: 0
face zones: 0
cell zones: 1

Overall number of cells of each type:
hexahedra: 226446
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 0

Checking topology...
Boundary definition 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
Left&Right 452892 454960 ok (non-closed singly connected)
Body 596 1192 ok (non-closed singly connected)
In 256 514 ok (non-closed singly connected)
Out 1216 2434 ok (non-closed singly connected)

Checking geometry...
Overall domain bounding box (-9.569 -10 -0.1) (15 10 0)
Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
Mesh has 3 solution (non-empty) directions (1 1 1)
Boundary openness (2.23116e-18 -1.32643e-18 7.69188e-20) OK.
Max cell openness = 2.3566e-16 OK.
Max aspect ratio = 377.225 OK.
Minimum face area = 6.5753e-07. Maximum face area = 0.100058. Face area magnitudes OK.
Min volume = 6.5753e-08. Max volume = 0.0100058. Total volume = 44.8375. Cell volumes OK.
Mesh non-orthogonality Max: 83.81 average: 8.67972
*Number of severely non-orthogonal (> 70 degrees) faces: 8.
Non-orthogonality check OK.
<<Writing 8 non-orthogonal faces to set nonOrthoFaces
Face pyramids OK.
Max skewness = 0.946479 OK.
Coupled point location match (average 0) OK.

Mesh OK.

End
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I would like to have some suggestions to solve this problem and to increase the quality of the mesh.

I also report the geometry.
Attached Files
 airfoil.txt (8.6 KB, 13 views)

 Tags gmsh, non-orthogonal, openfoam