[Albertine]

Hi,

I'm having this king of issue while meshing a gear, specifically I have troubles in correspondence of the tooth tip, some of them are meshed correctly straight while others become rounded. Since some of the are good I wouldn't say is a surfaceFeatures problem, but I really have no clues.

Can you suggest me some possible error sources? I think the problem is originated during the castellation phase.

Here are attached a screenshot of the .stl file, of the rounded tip and the correct one.

Thanks in advance

[Yann]

Something went wrong with your attachments and screenshots would definitely help!

[Albertine]

Originally Posted by Yann

Something went wrong with your attachments and screenshots would definitely help!

I'm sorry for the inconvenient, here are the pictures. I've investigated more and emerged that if I use nSmoothPatch 0, all the teeth are snapped correctly but roandmbly in some space between teeth some cells are wrongly created as in the third image. If I put nSmoothPatch >0 the spaces are correctly managed while some tooth tip are rounded.
I also tried to do 2 snapping phases a first one with nSmoothPatch >0 and then =0 to try to square the tooth tip but didn't work.
However, the mesh passed the checkMesh -allTopology, but I'm afraid that the simulation will struggle with such kind of cells.

[AtoHM]

You only have 2 cells across the tip. The snapping works well for the shown tooth thats aligned with the background mesh and not so well on the inclined tooth, where snapping is harder. Might be better with more cells. It appears at the whole front face, so i agree, its not an edge refinement issue.
Also I see you are using a non-uniform blockMesh. The more you deviate from cubic cells, the harder it will be for snappy to create a good mesh.


What I would try:
- increase the refinement level
- is a cylindrical blockmesh an option? it woule align each tip with the background mesh
- start with a uniform blockmesh
- nCellsBetweenLevels to 4 might help

[Albertine]

Originally Posted by AtoHM

You only have 2 cells across the tip. The snapping works well for the shown tooth thats aligned with the background mesh and not so well on the inclined tooth, where snapping is harder. Might be better with more cells. It appears at the whole front face, so i agree, its not an edge refinement issue.
Also I see you are using a non-uniform blockMesh. The more you deviate from cubic cells, the harder it will be for snappy to create a good mesh.


What I would try:
- increase the refinement level
- is a cylindrical blockmesh an option? it woule align each tip with the background mesh
- start with a uniform blockmesh
- nCellsBetweenLevels to 4 might help

Thank you for your answer, basically I have already tried your suggestions, the best result has been obtained with a higher refinement but still with some minor issues, but with a huge amount of cells. I ended up to have a less accurate geometry but with a reasonable number of cells.