Constantly running out of memory (can't select higher core count)

Hi everyone,

Brand new to Simscale, and having an issue with meshing. I’m using the free tier and unfortunately no matter what I do I run out of memory when meshing. I know this geometry is complex and it always fails on 4-core, but despite the core count setting saying “max 16”, I only ever get scheduled on 4-core machines, fail and then fail again on 8-core. Is there any way to force the mesh to occur on an 8-core machine by default?

I’ve gotten so far as the mesh exporting before it fails so it seems to be right on the line when it comes to the mesh completing.

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Hey ndanyluk,

Thanks for posting on the forum!

Have you referred to this article yet: Error: Machine Ran Out of Memory | SimScale Knowledge Base ?

Let us know if you are using these settings for your project since you are on the Community plan. Also feel free to share the project URL here for someone to take a closer look!

Best,
Satvik

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Hi @shenoy, thanks for your reply!

I have reviewed the article and I’ve tried decreasing my mesh fineness all the way down to 2 without success. I can’t select core counts in the community plan (it’s marked as a pro feature) so I have to use automatic.

Here’s the project: SimScale Login

There are two simulations in there, both have struggled with meshing, but I did eventually get a successful mesh with the incompressible sim. The CHT sim keeps failing to generate though.

Any help or guidance would be awesome and thanks so much!!

Best,
Nick

Hi @ndanyluk,

As I see it, it seems like you haven’t created a flow region for your model. This is necessary because it will delimit the place where the fluid will be in order for you to run a CFD analysis successfully. To observe the behavior of a flow region, take a look at this tutorial:

Or did I misinterpret and the model itself already corresponds to the flow region? Let us know so we can provide better support.

Best,
Igor

Hi @igaviano, I had issues creating a flow region given the many detailed faces of the model. Not sure if it was a geometry issue or in the way I was attempting to use the tool, but I could never get it to work. So instead I manually created one in the cad using a solid body and a boolean subtract with some cleanup steps.

In the CHT v2 simulation, the air volume is assigned to the “Flow Volume” part which represents the empty space in the model.

Hi @ndanyluk,

I see what you mean now. In this case, looking at the complexity of the flow region, do you see it as an option simplifying it even further? I say this because a model that detailed will require a very large mesh which will likely not be achievable using a community account.

Best,
Igor

Hi @igaviano thanks for taking a look and for the suggestion! I’ve gone ahead and removed a bunch of extraneous parts and features and was able to get a mesh but unfortunately I’ve had 2 simulations fail after around 70 iterations.

It looks like the simulations are diverging around the cutouts in the PCB that I’m using to get airflow down to the chip and caps on the bottom.

Things I’m thinking of:

  • simplify the cad by deleting the plastic “airflow blockers” I’m using to cover unwanted cutouts in the PCB and simply delete those holes in CAD (less boundary layers)
  • delete the top 5mm of the design where there is intricate features in the flow volume that don’t meaningfully impede or improve airflow
  • simplify the hard drives by removing the connectors and making them solid blocks without fillets

Is there anything else I could do to make this work? I’m consistently running out of memory on 2/4/8 core machines even though I get to the mesh export step every time.

My mesh quality settings have been stock except for:
Mesh 1:

  • Fineness = 3
  • Small Feature Suppression = 1e-4

Mesh 2:

  • Fineness = 4
  • Small Feature Suppression = 1e-5

Failing Mesh:

  • Fineness = 5
  • Small Feature Suppression = 1e-4

Hi @igaviano I got a few meshes to export! I went back and defeatured a ton of the design such that there are no more chamfers, fillets (except where relavant), empty screw holes, etc. Managed to get a mesh to export at Fineness 5 with Small Feature Suppression set to 1e-5.

Quality metrics could use a little work, the 99.99th percentile looks good but my maximums are way too high.

Hi @ndanyluk,

That’s great to hear and sorry for not following up earlier. If you manage to run the simulation, make sure to share the results in a new forum post.

Best,
Igor