SimScale CAE Forum

Problem with Surface refinement with Cell Zone


#1

Hi, my name is Antonio Targat, and I am having problems to mesh a geometry in SimScale. For some reason, I am not able to Mesh any geometries that contain Surface refinement with cell zones.

  • I am trying to Mesh three MRFs Zones and a porous zone within our geometry, in order to simulate rotating tires and fans, and Radiators respectively.
  • The Mesh operation fails within a couple of minutes of run-time with the following error message: A cell zone has been defined with assignments of faces. This is not supported. Please create a closed solid region that exactly represents your cell zone in your CAD tool.
    I already checked all of our solids for holes, and they all seem to be closed. An alternative MRF geometry was also constructed by using a boolean operation, as suggested by @ anirudh2821998 on the forum Issue with assigning mesh as the domain, which was also unsuccessful.
    I even tried to generate the STLs of the geometry in both CATIA and in Solidworks, with no success whatsoever.
    In my latest attempt, I tried Meshing an already generated Mesh with the same MRFs, which didn’t work.
  • Here is the link to the project: https://www.simscale.com/projects/leon_schmidtke/emc20_pre_season/
    Thank you.

#2

Hi @leon_schmidtke,
Here is the main reason of your mesh failure, you have assigned only 1 face for the surface refinement instead of assigning the volume to the surface refinement with cell zone option ON. Try again with the new assignments.

Cheers
Hamza Baig


#3

Hi @HamzaBaig ,
I’ve been messing around with our Geometry and I think the problem is that I can’t really upload a .STL geometry with of multiple solids or volumes. Somehow I can only upload them as an assembly of multiple faces, which in turn can’t get meshed with Cell Zones. I’ve been using a script that SimScale sent to our team a couple of Years ago to merge the STLs from all components into one single STL (https://drive.google.com/file/d/1t8zTQIJ_WU6-b7FWn2EqtNuMcbVqmJ7L/view?usp=sharing). Do you guys have any other approach to merging STL Files?
Thank you in advance,
Antonio Targat


#4

@leon_schmidtke: You can merge STL (text) files by hand, using a text editor (like Notepad++). I discussed it here : Forum topic on boundary layer


#5

Also check out the files here: Merging STL files - cheers!

Jousef


#6

Hi there,

I see dozens of geometries and models, so I’ll just be focusing on the latest one, and just a couple comment for the moment.

First check should be to have a domain with proper dimensions so that the splitting generates perfect cubes.

image

In your case, the bounding box dimensions are 27.825 x 7.192 x 7.2 m3. I would suggest to define the boundaries so that you have a bounding box of dimensions 25 x 7.2 x 7.2 m3. This should work with your current resolution (105, 30, 30) to get you cells of 0.24 m at refinement level 0.

I would avoid having the MRF cylinder so close parallel to the wall of the model. Either cleanly intersect the geometry or leave some room.

In this latest mesh, I can’t see the number of cells in the log file. But in one of the previous meshes, without the colling refiment you were already over 20 million. Maybe start with a slightly coarser mesh.

I’ll see if I can have a closer look this weekend.

Cheers,


#7

Hi @jousefm @Retsam
I tried merging the STL Files both manually and with the scripts that are here: Merging STL files ; and I still get an assembly of faces instead of an assembly of solids as result. I even checked the code of the files after both scripts ran and everything looks fine.

All solids are listed on the file, and they all start and end as I think they should…
In one of my uploads ( https://www.simscale.com/workbench/?pid=2840410787042819858&mi=geometry%3A175&mt=GEOMETRY) I somehow managed to upload two separate solids, but when I repeat the process using the full car geometry the same assembly of surfaces appears.
Do you guys have any other suggestions?
Thank you in advance,
Antonio Targat


#8

I’m having the exact same issue with my MRF zone not showing up as a solid, but rather a face and therefore not being able to create a cell zone within it. Here’s the link to my project: https://www.simscale.com/workbench/?pid=4446088511264372014&mi=spec%3A1a2e994f-3212-423b-b325-0e70174224f5%2Cservice%3AMESHING%2Cstrategy%3A20&ps=algorithm%2FFullSnappyHexMesh--oneOf%2Frefinements%2F6&sh=2

I was able to get an MRF zone that was a face to work last year with this project (in the UT 16 section): https://www.simscale.com/workbench/?pid=5893466710854457412&mi=spec%3A283aa552-dd48-4e4c-a7eb-458d179196f1%2Cservice%3AMESHING%2Cstrategy%3A48&ps=algorithm%2FFullSnappyHexMesh--oneOf%2Frefinements%2F8&sh=12 but for some reason the same method of defining a cell zone on an MRF is no longer working.

I’m also using an STL merging script.

Thanks in advance.


#9

Hi Wrenda,

I just want to add that we are having the same exact problem and also have the experiece, that last year we could use MRF zones on a face. The problem even arises on last years models that have proven meshes. The only difference between us, seems to be that I am not using a merger and have merged them all manually to make sure there are no errors. Hopefully this gets resolved soon.

Best Regards,
Jonas