[snappyHexMesh] Multi region mesh with snappyHexMesh

Matteo_Kamenjasevic · April 2, 2022, 11:05

Dear Foamers,
I am newie in multi region simulations and want to learn mesh this cases with snappyHexMesh. I watched a several videos on YT and I have to say that they are very bad and a lot of confusing. Also I tried to find something on internet and no success. This is my case: heatsink in which fluid flows through and it interfaces a solid with some high temperature. For me in this moment I am not so interese in physics I just want to use snappyHexMesh for multiregion simulations.
For creating groups and triangulation I am using Salome. My question is: should I define this interface between heatsink and solid like just one group, for example "heatsink_to_fluid"?

This is what I did:
For heatsink: "inlet", "outlet" and "walls_heatsink" (this walls are without interface ).
For solid: "walls_solid" (without interface).
And I set this interface like "heatsink_to_solid".
Then I exported this groups in STL files and set up snappyHexMeschDict.
When I run "splitMeshRegions -cellZones" it says that I have one region.
I hope that you can help me with this because I have a project in my Formula Student in Zagreb and want to provide some CFD simulations for my sub-team Cooling.

Hr_kules · April 5, 2022, 08:57

Hey Matteo,

maybe the chtmultiregionfoam tutorials would be helpfull? Especially the shell and tube heat exchanger does demonstrate quite well how to set up the snappyhexmesh and the usage of interfaces.

If this doesn't help you with the interfaces, after a lot of trial and error, in noticed that you can use the 'createPatch' dict to manually create mapped walls of disered surfaces.

Matteo_Kamenjasevic · April 6, 2022, 14:26

Hi, thank your for replying. Should I use createBafflesDict for chtMultiRegion simulations?

Hr_kules · April 7, 2022, 09:40

Nema problema,

i would say that this depends on your geometry, since I understood baffles as internal boundaries it could be mandatory, that you use createBafflesDict. However keep in mind, that you will need to define FaceZones prior to creating baffles. For the last case i worked on, where manually creating mapped walls was needed, i could use createPatchesDict.

If you use createBafflesDict, use topoSetDict to create the faceZones from the patches relevant for the interface

ismailsevimli · April 11, 2022, 04:10

I was at the same situations a month before. I tried to setup case like in Youtube videos as u mentioned. I am using OF9 .org version.In tutorials of chtMultiRegion "sheelTube heat exchanger" case solved my problem with salome CAD usage. (I prepared my geometry like heat sink tutorial on Youtube.) I just fit my problem with tutorial case and its works perfect now. U can check what to do in case with look at "Allmesh.layers" like files.

I hope its can help you, have a nice day.

April 2, 2022, 11:05	Multi region mesh with snappyHexMesh	#1
Matteo_Kamenjasevic New Member Matteo Join Date: Mar 2022 Posts: 4 Rep Power: 4	Dear Foamers, I am newie in multi region simulations and want to learn mesh this cases with snappyHexMesh. I watched a several videos on YT and I have to say that they are very bad and a lot of confusing. Also I tried to find something on internet and no success. This is my case: heatsink in which fluid flows through and it interfaces a solid with some high temperature. For me in this moment I am not so interese in physics I just want to use snappyHexMesh for multiregion simulations. For creating groups and triangulation I am using Salome. My question is: should I define this interface between heatsink and solid like just one group, for example "heatsink_to_fluid"? This is what I did: For heatsink: "inlet", "outlet" and "walls_heatsink" (this walls are without interface ). For solid: "walls_solid" (without interface). And I set this interface like "heatsink_to_solid". Then I exported this groups in STL files and set up snappyHexMeschDict. When I run "splitMeshRegions -cellZones" it says that I have one region. I hope that you can help me with this because I have a project in my Formula Student in Zagreb and want to provide some CFD simulations for my sub-team Cooling.

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April 5, 2022, 08:57		#2
Hr_kules Senior Member Nico Join Date: Jan 2022 Location: Germany Posts: 122 Rep Power: 6	Hey Matteo, maybe the chtmultiregionfoam tutorials would be helpfull? Especially the shell and tube heat exchanger does demonstrate quite well how to set up the snappyhexmesh and the usage of interfaces. If this doesn't help you with the interfaces, after a lot of trial and error, in noticed that you can use the 'createPatch' dict to manually create mapped walls of disered surfaces.

April 6, 2022, 14:26		#3
Matteo_Kamenjasevic New Member Matteo Join Date: Mar 2022 Posts: 4 Rep Power: 4	Hi, thank your for replying. Should I use createBafflesDict for chtMultiRegion simulations?

April 7, 2022, 09:40		#4
Hr_kules Senior Member Nico Join Date: Jan 2022 Location: Germany Posts: 122 Rep Power: 6	Nema problema, i would say that this depends on your geometry, since I understood baffles as internal boundaries it could be mandatory, that you use createBafflesDict. However keep in mind, that you will need to define FaceZones prior to creating baffles. For the last case i worked on, where manually creating mapped walls was needed, i could use createPatchesDict. If you use createBafflesDict, use topoSetDict to create the faceZones from the patches relevant for the interface

April 11, 2022, 04:10		#5
ismailsevimli New Member ismail sevimli Join Date: Jun 2020 Location: Istanbul,Turkey Posts: 1 Rep Power: 0	I was at the same situations a month before. I tried to setup case like in Youtube videos as u mentioned. I am using OF9 .org version.In tutorials of chtMultiRegion "sheelTube heat exchanger" case solved my problem with salome CAD usage. (I prepared my geometry like heat sink tutorial on Youtube.) I just fit my problem with tutorial case and its works perfect now. U can check what to do in case with look at "Allmesh.layers" like files. I hope its can help you, have a nice day.