SimScale CAE Forum

First try errors

Im trying to make a simple pipe fluid flow with a restriction in the pipe. The results are not reflecting the restriction. I initially had it set up as a wall but the error code said I need to have an advanced concept assigned to the surface so i used a momentum source for trial and error test. As a wall I’m getting the error that “wall 3 doesn’t belong to a volume region” and “multi region mesh used in single region analysis”. below is the link to my model, can anyone let me know what I’m missing or doing wrong?


For an incompressible analysis, you only need the flow region (the solid walls shouldn’t be in the domain). That’s the reason for the “multi region mesh” error that you received. You can either extract the flow region locally, in your CAD software, via Boolean/Combine operations, or in SimScale with a flow volume extraction operation.

Furthermore, the CAD model might also need a little clean up. This “restriction” part is a sheet body, which causes quite a lot of issues in CFD simulations.

So, summing up the steps:

  • Repair the CAD model, so all parts are solid;
  • Extract the flow region, making sure the model being used for the simulation consists of a single volume (the flow region)

Let us know if you run into issues!

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This worked, thanks. It looks like I needed to work more on just modeling the internal volume and that was creating the issue.

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