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Multi Region Mesh Issues - Star CCM+

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Old   September 26, 2018, 00:30
Default Multi Region Mesh Issues - Star CCM+
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MMH
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Hello all,

I am new to Star CCM+ and having problems performing mesh for a multi region. I am attaching some screen captures to present with a simplified model.

Generic Details about the model:
1. The model has three regions - a. Domain(Air), b. Radiator (Solid), c. Coolant(Liquid).

2. Target is to get temperature distribution across the radiator grid as coolant passes through.

3. The model was built in SolidWorks.

Few approaches adopted to simplify the model.
1. Surface model was adopted and reviewed carefully for mismatch.
2. Volume Control was applied to have conform mesh
3. Interfaces were created with exact same faces.
4. Imported the models separately both as regions and parts and modified as required.
5. All the models create volume mesh individually, not with other ones.


But I kept having problems such as
1. Surface not being oriented.
2. In one case, the volume mesh kept iterating over same correction for more than 5000 iterations and did not complete.

How should I approach the problem? Thanks in advance.
Attached Images
File Type: png Capture_Cross Section _Model.PNG (63.9 KB, 23 views)
File Type: png Surface Mesh_1.PNG (22.1 KB, 16 views)
File Type: png Volume Mesh_1.PNG (36.3 KB, 15 views)
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Old   September 26, 2018, 02:24
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I can't really tell what your geometry is from that image.


Did you get the coolant and air bodies in solidworks as well? I really don't recommend this approach, it's much easier just to generate them in STAR.


I would also recommend that (for any CHT model) you first just import your solids (in this case you have just the radiator) and mesh that by itself. This will often weed out a lot of other problems with interfaces and quality without a lot of the frustration. Usually while that mesh is happening I'm spending time in another simulation preparing the operations needed to extract the fluid volumes.


If you do want to use your solidworks fluid bodies, you will need to ensure that the contacts it imports are good. If they are not, you will have to do an imprint operation before volume meshing. The lack of imprinting is probably the cause of the issues you see in your current meshing strategy.
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Old   September 26, 2018, 09:21
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Thank you for your response.

As I have mentioned earlier, the model shown is a simplified model to mimic the same problem I have been facing with the full scale model.

I will attempt to process the solid volume next time and will keep you posted.

Thanks again.
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Old   September 27, 2018, 00:25
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Best approach to do this is by using only solid model and extracting other two fluids using volume extraction. It is hard to work with three FV and then checking errors and creating right interfaces.

So the method is,
  1. Work on solid geometry and import to CCM check for errors in surface repair.
  2. This solid should be manifold. otherwise volume extraction do not work.
  3. Now cap the inlet and outlet for any other domain (Like air or fluid) using fill holes operation
  4. Extract the volume using volume extraction option with solid and fill holes as parts
  5. Similarly do same for other domain
Because of this, you will automatically get the contacts for the interfaces. Just assign the part to region and they will appear.
Hope this helps!!!
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