SimScale CAE Forum

Cannnot create meshes anymore, out of memory error


#1

Here is my file project:
https://www.simscale.com/projects/OTsyganov/recumbet_fairing_from_matt/

It worked at first, but any mesh I’m trying to create now errors out with ‘out of memory’ error.
Also, I cannot use automatic mesh generation on STLs anymore.
I could make one on a parasolid model, but it still errors out even on very coarse mesh and using 16 cores.
What’s wrong? I’m a free user and just using CFD for hobby-level recumbent bike aerodynamics, hence I’m not very familliar with meshing and other esoteric aspects of CFD.


#2

Hi @OTsyganov,

The Parasolid geometry cannot work. Even ignoring the ‘out of memory’ indication, your parasolid geometry has way too many curved and joined surfaces. The fix would be to go back into CAD and ensure the entire outer surface is a single continuous surface, or at least reduce it to maybe 5 to 8 different faces max for the outer body.

Your STL fine seems fine however, and you can continue to use that mesh rather than trying to generate a new one. If you face the “out of memory” error for the STL mesh that has completed once, then you may have other projects in your dashboard that you might need to delete to free up some space.

Cheers.

Regards,
Barry


#3

The parasolid is reverse engineered from STL and converted back to STL in first case. Don’t ask why :stuck_out_tongue: Or maybe you can, but that would take a while to explain…
Can you explain why I can use automatic mesh on parasolid, but not on STL while we are at it?
And so it seems there is some disk size limit quota, not RAM quota? Is there a way to view it?


#4

Hi @OTsyganov, the new automatic mesher uses the geometry to be more automatic and produce better meshes, this information cannot be obtained from an STL, therefore for improvement purposes, the new automatic mesh generation tool needs to have the geometry and not a triangulated representation. I don’t believe there is a storage limit for having projects and data, however, each instance does have a limit as to how much it can hold. For example, a 96 core instance will likely be able to store more timesteps than a smaller one, I do not know however the relationship between instance size and storage of each instance, sorry.

I would recommend adding layers to your mesh, but this is actually a problem if your geometry only has one face.

Hope this helps a little,
Darren


#5

I see. Well, I’ve tried progressively ‘unrefining’ the mesh and finally got it to work.

Just for a sanity check:

Number of nodes: 8405244
Number of faces: 22370771
Number of volumes: 7064688
Number of tetrahedra: 0
Number of hexahedra: 6123778
Number of prisms: 155708
Number of pyramids: 0
Number of polyhedra: 785021

That’s the last mesh in this project, the bobtailed one:
https://www.simscale.com/projects/OTsyganov/recumbent_fairing_ramjet_v2/

Is it a properly refined mesh? Or ‘over-refined’?


#6

I cannot say about the refinement being over or under refined, this requires a mesh independence study, where if you search here on the forums you will get a very good picture about what that entails. Judging by the cell count in 7 million, I would guess it is sufficient.

I can however comment on the mesh setup and simulation based upon what I have found. The bounding box to me seems like it is too close to the geometry, and would interfear with results, unless you are trying to replicate some sort of experimental setup. The boundary walls, pressuming they shouldnt interfear, should be set as slip walls.

If you have any further questions I would be more than happy to help.

Best,
Darren


#7

Bah! Of course.
Slip on walls, non-slip on body, right?

No, this is just a ‘virtual wind tunnel’, and tried to make it smaller in an attempt to make it more manageable.


#8

Yes, boundary walls not passing fluid as slip, body walls as no-slip.

Ok, normally the cell count far field is pretty small so a little more space shouldn’t increase your memory footprint too much.

Best,
Darren


#9

Got that, will try and remake the mesh with larger box.


#10

While I’m at it: is there a way to duplicate a set of refinements and apply it to a different geometry, just like you would duplicate a simulation and apply it to a different domain?

Ok, you can, just duplicate the mesh and change geometry later.
I guess I’ll leave it here for posterity :slight_smile: