[snappyHexMesh] definition of boundary patches in snappyhexmesh

robboflea · April 4, 2019, 13:28

Hi all,

I am new to openfoam and I have a domain like the one below.

domain.png

All the external faces are walls besides the two rectangular inlet and outlet.
I would like to mesh it with snappyhexmesh. I have created a multi-zone stl file with three different zones: 'walls', 'inlet' and 'outlet'.
The problem is that I do not seem to understand how to go forward. Any help on a typical pipeline would be appreciated.

The problem is that I don't understand how to create the boundary patches. Should I create them from the very beginning, meaning when I set up the blocking in blockmesh? Or can the blockmesh grid be just a plain box without any info on boundary patches? If I should create an 'inlet' and 'outlet' boundary patch in blockmesh does this mean that I have to create two blocks in blockmesh like the ones in the figure below?

blocks.png

Thanks a lot for the help!

jackaroo · April 8, 2019, 08:30

Dear robbolea,

I've been having a similar issue when attempting to make a mesh for chtMultiRegionFoam where I have a single STL file that includes "walls" for a fluid domain that interface a solid, an inlet and an outlet.

After using snappyHexMesh I lose the patch info, even if regions are defined in the snappyHexMeshDict.

Did you manage to get anywhere with this?

Any help would be appreciated!

robboflea · April 8, 2019, 10:16

Hi Jackaroo,

in the end I gave up with snappy and I am now using cfmesh (it comes with OpenFOAM at least the version I am currently using v1812). The process is quite straightforward. After you create the stl file wih the boundary patches you have to run the surfaceFeatureEdges utility to make sure that edges in the geometry will be kept during meshing. After this you can run cfmesh (cartesianMesh or pMesh).

Hope this helps!

April 4, 2019, 13:28	definition of boundary patches in snappyhexmesh	#1
robboflea Senior Member Join Date: Nov 2011 Posts: 109 Rep Power: 14	Hi all, I am new to openfoam and I have a domain like the one below. domain.png All the external faces are walls besides the two rectangular inlet and outlet. I would like to mesh it with snappyhexmesh. I have created a multi-zone stl file with three different zones: 'walls', 'inlet' and 'outlet'. The problem is that I do not seem to understand how to go forward. Any help on a typical pipeline would be appreciated. The problem is that I don't understand how to create the boundary patches. Should I create them from the very beginning, meaning when I set up the blocking in blockmesh? Or can the blockmesh grid be just a plain box without any info on boundary patches? If I should create an 'inlet' and 'outlet' boundary patch in blockmesh does this mean that I have to create two blocks in blockmesh like the ones in the figure below? blocks.png Thanks a lot for the help!

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April 8, 2019, 08:30		#2
jackaroo New Member Jack Collins Join Date: Feb 2019 Posts: 1 Rep Power: 0	Dear robbolea, I've been having a similar issue when attempting to make a mesh for chtMultiRegionFoam where I have a single STL file that includes "walls" for a fluid domain that interface a solid, an inlet and an outlet. After using snappyHexMesh I lose the patch info, even if regions are defined in the snappyHexMeshDict. Did you manage to get anywhere with this? Any help would be appreciated!

April 8, 2019, 10:16		#3
robboflea Senior Member Join Date: Nov 2011 Posts: 109 Rep Power: 14	Hi Jackaroo, in the end I gave up with snappy and I am now using cfmesh (it comes with OpenFOAM at least the version I am currently using v1812). The process is quite straightforward. After you create the stl file wih the boundary patches you have to run the surfaceFeatureEdges utility to make sure that edges in the geometry will be kept during meshing. After this you can run cfmesh (cartesianMesh or pMesh). Hope this helps!