I’ve been working on setting up a compressible flow simulation for my FPV drone project and have successfully run basic tests on the bare frame. Now, after adding simplified models of electronics, motors, and propellers, I keep running into the following validation errors:
Errors I Am Facing:
Material Assignment Issue:
“Please ensure that all CAD entities are assigned a material or advanced concept. Missing material or advanced concepts were detected for the following entities: solid73.”
(click to select)
Rotating Zones & Material Assignment Conflict:
“Found 4 bodies only assigned to advanced concepts and not interfering with any body assigned to a material: solid82, solid83, solid85, solid84. Check your advanced concept and material assignments or the CAD model.”
(click to select)
Invalid Boundary Condition:
“Invalid boundary condition: Wall 1 has been assigned to at least one body without a material assignment: solid73. Please remove this body from the boundary condition assignment.”
(click to select)
What I Have Tried So Far:
Ensured all rotating zones (MRF) are correctly assigned to their respective propellers.
Verified that the flow region (air) is properly defined.
Deleted Solid73 from my CAD, but it still appears as an issue.
Attempted to re-assign materials to ensure every solid has either air or a rotating zone.
Checked boundary conditions to ensure they don’t reference deleted objects.
What I Need Help With:
I have been troubleshooting this for three days straight, trying different fixes. My main goal is to get a cool airflow visualization, even if it’s not the most mathematically precise simulation.
If anyone can help me correct my setup or guide me through what’s going wrong, I would be extremely grateful!
Any help would be immensely appreciated. Thank you!
Hi @Supervolant, thanks for posting on the forum and welcome to the SimScale Community
It’s a bit hard to pinpoint exactly where the issue is without having a look at your project - could you share it’s URL? Take a look at this guide to know how:
If you’re running an Incompressible study, make sure to delete all of the solids which aren’t fluid volumes from the project as this simulation type doesn’t take into account interactions between solids and fluids
Rotating zones are advanced concepts. On that note, they only define a cell region and aren’t actual bodies in your simulation - Documentation
Please see the attached screenshot for the latest error code. The mesh simulation ran for 90 minutes before the error occurred.
I have ensured that all bodies are properly closed (watertight) before exporting.
Regarding the rotating zones, after reviewing the documentation, I understood that in my case, I need to use cylinders to define the rotating zones. These should remain in the flow region and should not be removed during the initial setup.
I appreciate your help and look forward to your guidance!
You need to keep the cylinders and they should interfere with your flow region. You shouldn’t keep any solid bodies apart from the cylinders and the flow region.
Regarding your previous post,
I see that you’ve imported your CAD as STL. We usually avoid STL files for regular OpenFOAM studies (such as the one you’re running) since they are often faulty and lead to bad CAD entities - it’s better to go with a format that allows for polysurfaces such as STEP/Parasolid. This article might be helpful:
Keep in mind that, even if you’re not concerned with the actual physical results of the analysis, CAD issues might still cause problems in meshing. For instance, I see you’ve kept some unecessary details such as inscriptions:
I have remodelled all geometries and made them more simple by excluding unneccesary details and overall simplifying the mesh.
I am still getting meshing errors unfortunately. Yes I am importing .STL files, but I have designed using 3D’s Max and don’t have many more options for export.
The hex-dominant mesher is running for up to 600 minutes, resulting in errors, however In the end I am receiving data. Such as a cell count of ~20 million.
I have retried using the normal mesher, however I am receiving errors and failure within a few minutes now.
My plan is to now somehow convert and import the files using another file format. Maybe I can sign up for onshape and import my modell into that for later export that is more in alignment with the simscale archiecture. I will keep you updated and ff you have any other tips I am more than grateful to hear about it.
After using 3ds Max and importing my .STL files into Fusion 360, I was able to repair them and make them more usable for SimScale.
I finally managed to create a mesh and run a simulation without region refinements or rotating zones. However, after thoroughly reading the documentation and watching countless YouTube tutorials, I have to admit that I’m feeling a bit frustrated—I simply **can’t get any results whenever I try to insert rotating zones.
I can successfully create the mesh within 60 minutes and run a simulation without rotating zones. However, whenever I insert cylinders to define the rotating zones (which, in theory, shouldn’t affect meshing since I haven’t defined any region refinements or similar settings), the meshing process runs for over 400 minutes and restarts on a larger instance.
Maybe it is worth noting that I’m getting zero results with the standard mesher. Only the hex dominant mesher is leading me somewhere.
During the automatic restarts, the system even displays the number of created cells and logs the process, but the mesh itself never completes. I’ve attached a screenshot for reference.
It seems like your CAD model is much cleaner than before, which is great!
However, I still see some potential issues, as I’d mentioned this is why it’s so difficult to work with STL files for the OpenFOAM incompressible study. Something went wrong in the facet splitting of your model, for instance, and this small surface was generated:
You need to keep in mind that, as the standard/hex meshers work by fitting element faces onto surfaces, working with STL files will be inherently complex.
As a last comment, if your model is clean enough, there is no issue in using the Standard mesher - which I would strongly advise you to do since it’s simpler to work with.
