[twinturbotom]

I have a block mesh with cell zones created by splitMeshRegions. I would like to remove all cells in one of the zones, creating a void in the mesh.

What is the best approach?


blockMeshDict blocks:

blocks
(
    hex (0 1 2 3 4 5 6 7) domain (20 6 10) simpleGrading (1 1 1)
    hex (8 9 10 11 12 13 14 15) interior (4 2 2) simpleGrading (1 1 1)
);

Cell Zone command after blockMesh:

splitMeshRegions -cellZones -overwriteblocks

Right now I'm working with OF 3 and looking into topoSet, setSet, and other utilities after following references listed in another post (http://www.cfd-online.com/Forums/ope...checkmesh.html ). At this point I haven't been able to successfully cut out my "interior" block cell zone.

I look forward to seeing how others approach this. Thank you!

[Antimony]

Hi,

You can use subsetMesh in conjunction with topoSet.

Use topoSet to create a cellSet that you want to remove. Invert the cellSet so that it keeps everything else except the region that needs to be excluded.

Run subsetMesh with the name of the cellSet and voila, you will get the mesh with the particular zone removed.

Hope this helps.

Cheers,
Antimony

[twinturbotom]

Antimony, I appreciate your response. The invert set followed by subSet command cut out my obstruction in a new cell set! Your input was very helpful!


The new set has not altered the internal mesh as viewing the "internal mesh" in paraView shows the obstruction meshed.

The obstructed set is exactly what I would like to use, any suggestions on how to instruct my solver to use the obstructed set and not the internal mesh? Is this just a matter of somehow selecting the subSet faces and defining proper wall/patch conditions?

For completeness. I used setSet interactively to define the set and cut it out (only a domain block, not obstruction block or splitMeshRegion used):

cellSet obstruction new boxToCell (1 1 0) (3 2 1)
cellSet obstruction invert
cellSet obstruction subSet

[Antimony]

Hi,

I don't quite follow what exactly do you want to do. Do you have an image or something to graphically represent what is it that you are trying to get?

Unless the -overwrite tag is specified, subsetMesh will write the subsetted(if there is such a word) mesh to a new time folder.

Cheers,
Antimony

[twinturbotom]

Thank you for the follow up.
Below is a rough idea of what I'm looking to accomplish; flow moving over an obstruction.

I understand the obstruction is too close to the inlet and the mesh resolution is very poor. Right now I'm just looking to determine how to capture an obstruction with blockmesh. I do have a working model when I use multiple blocks from blockmesh but as the complexity increases I prefer not too.

Eventually some of he obstruction faces will be inlet/outlets to the model (along with the domain inlet/outlet).

The two images are:
1. Flow through domain with an obstruction that is not properly defined
2. mesh of the cellSet with obstruction. IF I were to select "Internal Mesh" in paraView, the cutout would not be present.




Thanks.

[twinturbotom]

Antimony,
I was using setSet's interactive subSet which didn't work like "subsetMesh".
Once I used subsetMesh with my obstruction cellSet it worked perfectly!

Thank you!

I'll post a completed description of what I did once I work through a few improvements in meshing my obstruction. I have to learn how to select/define mesh and patch condition of the obstruction faces.

[Antimony]

Hi,

I was just wondering how it is that you were unable to get the region removed in the internalMesh. Your explanation on setSet helped to clear that up.

Personally, I have not used setSet. Rely more on topoSet and/or subsetMesh to get things done.

Just a couple of heads up on subsetMesh. Once you have cut out the obstruction from the blockMesh, the faces of the obstruction will by default be lumped together in "oldInternalFaces". In case you want to split them, you can use topoSet via the faceSet "normalToFace" option and specifying the normal for each of the faces. At least that is the workable solution that I was able to come up with.

Hope this helps.

Cheers,
Antimony

[baran khaksari]

Hi friends
I try to simulate a tunnel with one inlet and one outlet in front and back of it. The heat source is in the middle. when I simulate it with para view, some faces are missed, when I checked internalMesh. Also, when I run the simulation with buoyantBoussinesqPimpleFoam, the solver I used, time is negative????!!!!!
The attached file is my blockMesh and 0 file.
Please help me to find out.
thanks.
0.tar.gz

system.tar.gz

datauri-file.png

[frantov]

Thanks for this post.

It has allowed me to generate a half sphere mesh with an inlet.


whole_sphere.png
half_sphere_mesh.png


Steps:
1. Generate whole sphere mesh using blockMesh See tutorials/mesh/blockMesh/sphere

2. Delete half sphere mesh using topoSet + subsetMesh.
3. Step 2 generates an "oldInternalFaces", checkMesh, fails. Then I use createPatch to set "oldInternalFaces" as wall. checkMesh OK.
4. Use topoSet to generate an inlet using a cylinderToCell
5. Create inlet using createPatch


To have these operations organized I created folders for the topoSet and patch operations. Then I took advantage of the argument -dict, which allows you to call the dictionaries from a folder.

Attached is the system folder, in case is useful or any suggestions are welcome.



blockMesh
topoSet -dict system/topo1/topoSetDict
subsetMesh topRegion -overwrite
createPatch -dict system/patch1/createPatchDict -overwrite
topoSet -dict system/topo2/topoSetDict
createPatch -dict system/patch2/createPatchDict -overwrite
system.zip