[snappyHexMesh] Meshing small features

appie · October 2, 2014, 08:52

Hi everybody!

When I mesh with snappyHexMesh, some features in my stl are being ignored. The geometry is of order 10 m, but is has some tubes in the centre of 5cm diameter in the centre. At the moment, sHM ignores these small tubes.

How can I make sHM mesh these small features? Can I set a minimum size that sHM should look for?

Many thanks in advance!

Appie

wyldckat · October 11, 2014, 12:49

Greetings Appie,

snappyHexMesh is only able to see as much as the base mesh is able to provide.
Therefore, if for example, your base mesh is composed of 1m sided cubes, it's only natural that only the surfaces that are present in 2 or more cubes will be visible. Otherwise, they're just 5cm ants

It's also true that if there are some larger surfaces are seen by snappyHexMesh and have enough refinement assigned to them, then it might be enough refinement nearby those tubes for them to be seen as well.

Best regards,
Bruno

appie · October 16, 2014, 03:20

Dear Bruno,

Many thanks for clarifying how snappyHexMesh deals with this. I was hoping for some workaround, but is doesn't seem to be easy.

In the end, I think that one should try to avoid these scale separation as I am currently having, because it always makes it hard to mesh nicely. Unfortunately the surface of the tube is very important to the case.

Anyhow, thanks again!

Appie

October 2, 2014, 08:52	Meshing small features	#1
appie New Member Join Date: Jul 2014 Posts: 6 Rep Power: 11	Hi everybody! When I mesh with snappyHexMesh, some features in my stl are being ignored. The geometry is of order 10 m, but is has some tubes in the centre of 5cm diameter in the centre. At the moment, sHM ignores these small tubes. How can I make sHM mesh these small features? Can I set a minimum size that sHM should look for? Many thanks in advance! Appie

October 11, 2014, 12:49		#2
wyldckat Retired Super Moderator Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,975 Blog Entries: 45 Rep Power: 128	Greetings Appie, snappyHexMesh is only able to see as much as the base mesh is able to provide. Therefore, if for example, your base mesh is composed of 1m sided cubes, it's only natural that only the surfaces that are present in 2 or more cubes will be visible. Otherwise, they're just 5cm ants It's also true that if there are some larger surfaces are seen by snappyHexMesh and have enough refinement assigned to them, then it might be enough refinement nearby those tubes for them to be seen as well. Best regards, Bruno wilsonrcf likes this. __________________ OpenFOAM: FAQ \| Getting started Forum: How to get help, to post code/output and forum guide Read this before sending me PM

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October 16, 2014, 03:20		#3
appie New Member Join Date: Jul 2014 Posts: 6 Rep Power: 11	Dear Bruno, Many thanks for clarifying how snappyHexMesh deals with this. I was hoping for some workaround, but is doesn't seem to be easy. In the end, I think that one should try to avoid these scale separation as I am currently having, because it always makes it hard to mesh nicely. Unfortunately the surface of the tube is very important to the case. Anyhow, thanks again! Appie