[mariloo]

Hello everybody, I am new to this forum. I am facing some problems when running checkmesh on Openfoam, in fact I get some errors and I've spent days trying to improve my mesh (I use Gmsh), but without any results.
Does anybody have an idea on how to fix this? Thanks id advance.

This is the error I get:

Checking geometry...
Overall domain bounding box (-0.999 -1.665 -0.1) (4.995 1.665 0)
Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
Mesh has 3 solution (non-empty) directions (1 1 1)
Boundary openness (-4.67483e-18 -3.16565e-18 9.91875e-17) OK.
***Open cells found, max cell openness: 1, number of open cells 43
<<Writing 43 non closed cells to set nonClosedCells
<<Writing 3 cells with high aspect ratio to set highAspectRatioCells
Minimum face area = 4.99645e-09. Maximum face area = 0.164094. Face area magnitudes OK.
***Zero or negative cell volume detected. Minimum negative volume: -8.26824e-11, Number of negative volume cells: 2
<<Writing 2 zero volume cells to set zeroVolumeCells
Mesh non-orthogonality Max: 161.036 average: 23.3116
*Number of severely non-orthogonal (> 70 degrees) faces: 279.
***Number of non-orthogonality errors: 38.
<<Writing 317 non-orthogonal faces to set nonOrthoFaces
***Error in face pyramids: 50 faces are incorrectly oriented.
<<Writing 48 faces with incorrect orientation to set wrongOrientedFaces
Max skewness = 3.12096 OK.
Coupled point location match (average 0) OK.

Failed 4 mesh checks.

[mzzmrt]

The problem is not the checkMesh but the script. The script is indeed an interesting effort for boundary layer meshing but the quality of the mesh produced, specially in the bl is no good.


So I can advise two options for this kind of problem:


1. Use the native boundary layer function (field actually) of the gmsh. It is more effective, fast and easy.


2. Install and use the open-source tool Construct2D for meshing fully hex, probably the best option at all.

[mariloo]

Thank you very much for your advices. The problem is that I wanted to do a 3D mesh but Gmsh supports only a 2D boundary layer mesh.

[mzzmrt]

You can always extrude this 2D boundary layer mesh to get 3D for simple wing geometries easily if you are looking for a pseudo-3D mesh for OpenFOAM.



On the other hand, if your 3D wing geometry is too complex this will be a different story.

[Artur.Ant]

Recently I had the same problem and I solved it decreasing a little the number of cells within BL keeping y+<1

[Artur.Ant]

Some ubdate on this:

After some other manipulation of the mesh I concluded that creating manually the boundary layer is not possible because of how the geometry is treated by Gmsh (especially in zones with curvature).

What I usually do is to create a structured mesh (especcially near walls) and to generate the BL with snappyHexMesh in OpenFoam.

Otherwise maybe one sould use the boundary layer function implemented in GMSH and not creating by hand the boundary layer.