[mesh manipulation] mirrorMesh is not preserving the mesh regions

Zena27 · April 11, 2023, 07:18

Hello all,
I have a cylinder that is divided in two regions. I already specified the regions when I am creating it on blockMesh, the problem is that when I mirror the mesh it loses all the data about the regions and it treats it as just one region.

Is there any solution for this? I am using OFv2212

ERodriguez · July 4, 2023, 07:37

Hi Zeinab
Did you find the answer to this? I am going through your same problem ...
Regards

Zena27 · July 4, 2023, 08:18

Hello,
actually no. Also, as far as I remember, the regions are not mirrored (also but not sure the cellzones). I could find a turn around to define the regions after mirroring.

You can tell me what would you like to do and I can try to help you with your case.

ERodriguez · July 4, 2023, 09:07

Hi
Thanks for the quick answer

I have a relatively complex region in which I define several porous media through cellZones (I could work with cellSets also and then convert the sets into zones by using topoSet)

I have only meshed half of my domain because the geometry is a bit complex and it is easier. However, the flow is not symmetric so I need to simulate my whole domain. Imagine a C-shaped pipe, I can mesh only half of it but in order to simulate inlet and outlet I need to simulate the whole domain.

I am meshing by using another software and then converting into OpenFOAM format for half of my domain and I wanted to use mirrorMesh to duplicate my mesh. However, I am not keeping the cellZones so I would need to redefine all my porous media cellZones in order to assign their properties.

I think my problem was related to yours and also THIS post.

I might be able to redefine the cellZones after the mirrorMesh operation. However, the regions are rather complex and I would rather just use the cellZones that I have created in my meshing software directly into the OpenFOAM mesh.

Let me know if I could make anything clearer

Best regards

Zena27 · July 6, 2023, 10:05

Hello,

sorry for the late reply. I don't think that there is way of doing it other than defining the cellZones again after mirroring, or by coding it.

I don't know about your case specifically but you can think about automating the generation of the cellZone using python.

ERodriguez · July 14, 2023, 04:18

In case it is useful for someone in the future
At the end I found a workaround by using surfaceToCell in topoSet so I had to define (externally) *.stl files so the cells inside them were selected as my porous media. The bad thing about this approach is that sometimes cells near the boundary of the STL were wrongly selected so it required a lot of manual tweaking based on unselecting discrete cells based on their coordinates.
Anyway, it worked ...
Regards

April 11, 2023, 07:18	mirrorMesh is not preserving the mesh regions	#1
Zena27 Member Zeinab Join Date: Feb 2023 Posts: 32 Rep Power: 3	Hello all, I have a cylinder that is divided in two regions. I already specified the regions when I am creating it on blockMesh, the problem is that when I mirror the mesh it loses all the data about the regions and it treats it as just one region. Is there any solution for this? I am using OFv2212

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July 4, 2023, 07:37		#2
ERodriguez New Member Eduardo Join Date: Feb 2019 Posts: 9 Rep Power: 7	Hi Zeinab Did you find the answer to this? I am going through your same problem ... Regards

July 4, 2023, 08:18		#3
Zena27 Member Zeinab Join Date: Feb 2023 Posts: 32 Rep Power: 3	Hello, actually no. Also, as far as I remember, the regions are not mirrored (also but not sure the cellzones). I could find a turn around to define the regions after mirroring. You can tell me what would you like to do and I can try to help you with your case.

July 4, 2023, 09:07		#4
ERodriguez New Member Eduardo Join Date: Feb 2019 Posts: 9 Rep Power: 7	Hi Thanks for the quick answer I have a relatively complex region in which I define several porous media through cellZones (I could work with cellSets also and then convert the sets into zones by using topoSet) I have only meshed half of my domain because the geometry is a bit complex and it is easier. However, the flow is not symmetric so I need to simulate my whole domain. Imagine a C-shaped pipe, I can mesh only half of it but in order to simulate inlet and outlet I need to simulate the whole domain. I am meshing by using another software and then converting into OpenFOAM format for half of my domain and I wanted to use mirrorMesh to duplicate my mesh. However, I am not keeping the cellZones so I would need to redefine all my porous media cellZones in order to assign their properties. I think my problem was related to yours and also THIS post. I might be able to redefine the cellZones after the mirrorMesh operation. However, the regions are rather complex and I would rather just use the cellZones that I have created in my meshing software directly into the OpenFOAM mesh. Let me know if I could make anything clearer Best regards

July 6, 2023, 10:05		#5
Zena27 Member Zeinab Join Date: Feb 2023 Posts: 32 Rep Power: 3	Hello, sorry for the late reply. I don't think that there is way of doing it other than defining the cellZones again after mirroring, or by coding it. I don't know about your case specifically but you can think about automating the generation of the cellZone using python.

July 14, 2023, 04:18		#6
ERodriguez New Member Eduardo Join Date: Feb 2019 Posts: 9 Rep Power: 7	In case it is useful for someone in the future At the end I found a workaround by using surfaceToCell in topoSet so I had to define (externally) *.stl files so the cells inside them were selected as my porous media. The bad thing about this approach is that sometimes cells near the boundary of the STL were wrongly selected so it required a lot of manual tweaking based on unselecting discrete cells based on their coordinates. Anyway, it worked ... Regards