# Meshing problem with finer mesh

Hello there guys, im having a little bit of problem to get a finer mesh with SnappyHexMesh, the error said that i need to alocate more memory to the computer, but im using a 32 core one. The odd thing is that i can manage to produce a very fine AutoSnappyHexMesh, but this one does not fit my requirements.

Thank you very much for your help!

@murillocs - is it a public project? That way I could directly have a look at your mesh settings and provide a tailored answer.

Best,

David

Yes it is

@murillocs - alright, I found your project and had a quick look. I guess you’re referring to this project: https://www.simscale.com/projects/murillocs/front_airfoil_formula_sae

In your mesh settings, you added refinements where you allow the a maximum refinement of level 9 (see screenshot).

These levels refer to the octree-refinement approach. This means with each level, one cell is split into 8 cells. So if we make this computation for 9 levels, we end up with:

$$1 \cdot 8^9 = 134217728$$

So even if only one cell would be refined to a level of 9, you’d end up with a huge number of cells that can not be handled anymore by a reasonable machine. Therefore, I’d suggest that you rather start with a max level of 5 or 6 and see if you really need a higher level of refinement.

Another question: What CAD software did you use to create the wing? It looks great - but the many split faces on the surface are odd. It would be nicer if this would be one nurbs face, so the export seems to be split those faces…

On a related note - @Ali_Arafat and @sjoshi put together a very helpful explanation on this meshing operation that you can find in via this link: https://docs.simscale.com/docs/content/preprocessing/meshing/meshing_general.html#reference-shm That meshing approach can be a bit tricky in the beginning but once the approach is understood, it’s super powerful.

Following @dheiny reply, your maxGlobalCells is set to be 15 million, while the refinement levels will give you more than that. Your blockMesh already returns a size less than one meter and from experience, such a high level of refinement means mega million cells.

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Thank you very much for your help!!!
In regard of the level 9 refinement, i have used level 9 refinement before with no problems that is why i tried again. And i used soliworks to create the geometry.

Again thank you for your help, I will keep in touch if it works.

@murillocs - regarding the level 9 refinement: Since you only indicated it as a “Maximum refinement” level the meshing algorithm can go up to that level of refining but doesn’t necessarily do it. So it could be that it worked but it was not refined up to this level.

Regarding using Solidworks: Is the wing-surface in solidworks also split in multiple faces? So can you select there also different faces? I’m wondering if this splitting is due to the modeling approach behind this wing surface or the STEP export of Solidworks.

The problem with multiple faces is it with solidwork… because i need multiple points to create the splice, he also creates multiple faces…