[snappyHexMesh] blockMesh for multi-region snappy

kandelabr · June 7, 2018, 18:19

I set up a multi-region case, meshing with snappyHexMesh. It seems to do its job but I have problems with outermost faces.

I create a background mesh with blockMesh, leaving the blockMeshDict.boundary empty so that defaultFaces is assigned. Usually I make background mesh just slightly bigger so snappy snaps easily and assigns my 'real' patches.

But in multi-region setup, snappy creates new regions where the cells should have been removed because they were outside my model.

If I make background mesh of exactly the same dimensions than my model (if it's a block, that is), I'm stuck with defaultFaces again.

I could remove domain*/ folders and use changeDictionary and whatnot but I don't think that's the right way to do it.

In the tutorial, blockMesh defines named boundary faces - that's what I can't / don't want to do. Tutorials from holzmann-cfd.com use a mesh created in SALOME...

How do I really set up a multi-region snappyHexMesh?

Thanks!

simrego · June 12, 2018, 05:45

Hi!

What version do you use? In +v1712 (maybe in 1706 and 1612 too) you can define the inside points for the regions you want to keep, and it removes the regions you don't need, and you will have correct boundary names, conform mesh between regions, etc..

kandelabr · June 12, 2018, 06:25

I'm currently using Turbomachinery CFD's package in which I believe version 5.x is used from OF Foundation. However I'm switching to ESI-CFD's latest version because there's a blended wall function I really need. I'll check snappyHexMesh too and report back.

Thanks!

simrego · June 12, 2018, 06:57

In v1712 check the $FOAM_UTILITIES/mesh/generation/snappyHexMesh/snappyHexMeshDict file. You will see there how can you define multiple regions with the locationsInMesh entry (i think this part is commented).

Good luck!

June 7, 2018, 18:19	blockMesh for multi-region snappy	#1
kandelabr Senior Member Nejc Join Date: Feb 2017 Location: Slovenia Posts: 196 Rep Power: 9	I set up a multi-region case, meshing with snappyHexMesh. It seems to do its job but I have problems with outermost faces. I create a background mesh with blockMesh, leaving the blockMeshDict.boundary empty so that defaultFaces is assigned. Usually I make background mesh just slightly bigger so snappy snaps easily and assigns my 'real' patches. But in multi-region setup, snappy creates new regions where the cells should have been removed because they were outside my model. If I make background mesh of exactly the same dimensions than my model (if it's a block, that is), I'm stuck with defaultFaces again. I could remove domain/ folders and use changeDictionary and whatnot but I don't think that's the right way to do it. In the tutorial, blockMesh defines named boundary faces - that's what I can't / don't want to do. Tutorials from holzmann-cfd.com use a mesh created in SALOME... How do I really* set up a multi-region snappyHexMesh? Thanks! Last edited by Tobi; June 24, 2020 at 13:05.

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June 12, 2018, 05:45		#2
simrego Senior Member anonymous Join Date: Jan 2016 Posts: 416 Rep Power: 14	Hi! What version do you use? In +v1712 (maybe in 1706 and 1612 too) you can define the inside points for the regions you want to keep, and it removes the regions you don't need, and you will have correct boundary names, conform mesh between regions, etc..

June 12, 2018, 06:25		#3
kandelabr Senior Member Nejc Join Date: Feb 2017 Location: Slovenia Posts: 196 Rep Power: 9	I'm currently using Turbomachinery CFD's package in which I believe version 5.x is used from OF Foundation. However I'm switching to ESI-CFD's latest version because there's a blended wall function I really need. I'll check snappyHexMesh too and report back. Thanks!

June 12, 2018, 06:57		#4
simrego Senior Member anonymous Join Date: Jan 2016 Posts: 416 Rep Power: 14	In v1712 check the $FOAM_UTILITIES/mesh/generation/snappyHexMesh/snappyHexMeshDict file. You will see there how can you define multiple regions with the locationsInMesh entry (i think this part is commented). Good luck!