[snappyHexMesh] Modelling Rotor: To use MergeMeshes or not?

nialloneill · September 21, 2023, 05:45

Hello, I am modelling a wind turbine rotor and am trying to figure out the best way to do it.

For now I am using snappyHexMesh and am having significant difficulties getting a good snap quality. I have seen some examples where people create a mesh of the rotating region and a mesh of the non rotating region, and then merge the meshes after. Is this a good practice?

Thanks

Alczem · September 25, 2023, 03:48

Hey

It is what I usually do when I am not satisfied with snappyHexMesh. Make sure that the coupled patches match pretty well, and don't forget to change the boundary file to create the ACMIs once the meshes are merged together.

AtoHM · September 25, 2023, 07:00

my 2 cents:
When not using overset mesh, having stationary and rotating parts in the same model usually requires using different meshes and coupling through interfaces. So, what Alczem already states, plus I'd like to point out, that ACMI interfaces are not mass-conservative. openfoam.org has introduced a new interface algorithm called NCC which is mass-conservative and replaced ACMI in the recent releases: https://cfd.direct/openfoam/free-sof...rmal-coupling/

September 21, 2023, 05:45	Modelling Rotor: To use MergeMeshes or not?	#1
nialloneill New Member Niall O'Neill Join Date: Feb 2023 Posts: 21 Rep Power: 3	Hello, I am modelling a wind turbine rotor and am trying to figure out the best way to do it. For now I am using snappyHexMesh and am having significant difficulties getting a good snap quality. I have seen some examples where people create a mesh of the rotating region and a mesh of the non rotating region, and then merge the meshes after. Is this a good practice? Thanks

September 25, 2023, 07:00		#3
AtoHM Senior Member M Join Date: Dec 2017 Posts: 694 Rep Power: 12	my 2 cents: When not using overset mesh, having stationary and rotating parts in the same model usually requires using different meshes and coupling through interfaces. So, what Alczem already states, plus I'd like to point out, that ACMI interfaces are not mass-conservative. openfoam.org has introduced a new interface algorithm called NCC which is mass-conservative and replaced ACMI in the recent releases: https://cfd.direct/openfoam/free-sof...rmal-coupling/ Alczem likes this.

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September 25, 2023, 03:48		#2
Alczem Senior Member Join Date: Dec 2021 Posts: 235 Rep Power: 5	Hey It is what I usually do when I am not satisfied with snappyHexMesh. Make sure that the coupled patches match pretty well, and don't forget to change the boundary file to create the ACMIs once the meshes are merged together.