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-   -   Empty cellZones, faceZones and pointZones files after mesh merging (http://www.cfd-online.com/Forums/openfoam-meshing-snappyhexmesh/117294-empty-cellzones-facezones-pointzones-files-after-mesh-merging.html)

vasava May 6, 2013 08:19

Empty cellZones, faceZones and pointZones files after mesh merging
 
I am simulating fluid mixed by an impeller. Here is what I did
1. I divided the domain in to two parts: a. Region close to the impeller blades. b. The mixing tank (minus the region described by 'a').
2. Created two meshes.
3. Use mergeMesh operation to merge the mesh.

Now when I check the merged mesh the cellZones, faceZones and pointZones files are empty. What do you think is going wrong?

Two more questions about the stl file.
1. Should the stl file be exported as one surface or exported as one file containing several surfaces (inlet, outlet, wall etc)?
2. If we export the stl file as one surface how do we generate patches (inlet, outlet, wall etc)?

ngj May 6, 2013 08:34

Hi Vasava,

Did you have any cell-, face- or pointZones in the two original meshes?

The thing is that these zones are something, which you need to create, and which serve particular purposes depending on your solver. Hence, if you did not have any before the merging, then it is just fine that they are empty. Their presence is probably due to the merging utility, which writes all fields/information potentially present.

Kind regards

Niels

vasava May 7, 2013 01:18

Quote:

Originally Posted by ngj (Post 425559)
Hi Vasava,

Did you have any cell-, face- or pointZones in the two original meshes?

No Niels, I did not have them. And that it why I was asking about the nature of the stl file. I tried working with stl file with one surface and stl file with multiple surface (inlet, outlet etc). Right now nothing seems to work.

Thanks for the answer.

ngj May 7, 2013 03:25

Hi Vasava,

I didn't notice the question about the stl-surfaces. Are you using snappyHexMesh to generate the meshes? And what are the problems that you encounter?

I have generated simple meshes with both one and multiple stl-surfaces, so neither should be a problem. In case you only have one stl-surface, you can look into

Code:

createPatch -help
The source code and an example of a dictionary placed here

Code:

<OFPATH>/applications/utilities/mesh/manipulation/createPatch
This utility allows for the splitting of one patch into multiple names and types.

Kind regards

Niels

vasava May 7, 2013 04:43

Quote:

Originally Posted by ngj (Post 425755)
I didn't notice the question about the stl-surfaces. Are you using snappyHexMesh to generate the meshes? And what are the problems that you encounter?

Yes, I am using snappyHexMesh to generate meshes. The problem is when I merge the meshes I see that the files (i mention earlier) are empty. I checked the individual meshes. There too the files are empty.

I am now following the tutorial 'propeller' to see if I can find some hints.

Thanks for your answer.

ngj May 7, 2013 04:53

Hi Vasava,

Let me just stress one thing:

If your solver does not need cell-, face- or pointZones, then it is perfectly fine that these files are empty.

Good luck,

Niels


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