ways to create cellZones and faceZones
I've been playing around a lot with the creation of cellZones and faceZones and here is what I have to report !
Till now I have found 3 ways to do it. ( I am sure there are more)
1. To use setSet utility and cellZonesSet and faceZoneSet commands.
This works amazingly well and creates the zones. A small problem can arrise if you are trying to set zones for an internal flow case and at the center of your geometry you have level 0 cells. These cells are not properly broken down and hence your zone is not exactly what you think it is. The work around for this is to just have a higher resolution where there are level 0 cells.
2. Using snappyHexMesh to create the zones.
Even this method does a very good job but somehow, atleast for my geometry, I see stitched kinda break where the cellZones starts and ends and where there is a faceZone. I have a strong feeling this might be because of the stl quality but I am quite sure that it is pretty decent.
Here are the pics.
The break in the second picture is where I have a faceZone.
3. This is something which I stumbled upon unintentionally ( i am so glad I did) - Using setSet utility but for blockMesh.
In method-1, the setSet command is used for the latest time step created by snappyHexMesh or for the mesh imported from other places but if you want to mesh in snappy and you want to create zones and don't want to see the problems which you saw in method-1 or method-2, the best way to do this is to actually create the cell and faceZones for the blockMesh. I accidentally did this when I forgot to use the -latestTime tag for method-1. This seems to be the best I saw. It doesn't have the breaks from method-2 nor does it have the extra cells from method-1
Here are the pics.
I just wanted to share this info with all of you and see if you have any suggestions.
There are 2 things which perplex me in the meshes which I uploaded. The geometry just infront of the cylindrical section has a lot of polyhedral cells. It is a very very simple geometry ( diverging section) and I am really surprised that snappy is not able to put hex cells there. Also, the featureEdge setting is put to 160 so that it captures all the curves ( as a matter of fact it does) but unfortunately, the circles aren't really round ! I have the nFeatureSnapIter at 10. Is there anything else I can do to improve this?
Sorry for the long post. Hope this info helps :-)
Thank you for sharing your experience
Could you please let me know how can I execute setSet to get the faceZone without using snappyHexMesh?
I have an STL file and want to create the faceZone according to it .. how can I do it?
I don't know what to choose between all of those:
Appreciate your help
Ok I found out how to create cellSets from surface:
cellZoneSet cZone new surfaceToCell ".../constant/triSurface/Umb.stl" ((0 0 20)) false false false 0.3 -100000
Then faceSet from cellSet:
faceZoneSet fZone_all new cellToFace cZone all
Then faceZone out of faceSet:
faceZoneSet FFF new setToFaceZone fZone_all
So now when I ran Snappy those faces did not snap!
Can you please explain what did you do?
Glad that you have done something extremely well. I would like to borrow method to create faceSets for simple blockMesh. Lets say i have similar geometry like you (cylinder of length L). I wanted to create faceSets at 10 different locations along the length.
Can you please help me?
Try using searchableCylinder ahen running topoSet (or setSet). by using different end point locations you can then select various parts of the mssh cylinder you're interested in. Mjch like you would slice a salami :)
now i kno how to use them :)
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