# How to create zero thickness internal walls in a given mesh in OpenFOAM?

I know using topoSet and subsetMesh along the lines of the mesh/moveDynamicMesh/simpleHarmonicMotion tutorial, one can cut holes into a mesh and obtain new patches. How can something similar be achieved with a vanishing hole, i.e. can a set of internal faces be turned into two touching patches with opposite orientation?

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 also asked at cfd-online.com/Forums/openfoam-meshing/… – kar Jul 6 '12 at 10:34 When you write "vanishing hole" do you mean that you would like to dynamically select a set of faces within a single mesh, that should be cut out as the static cells in this tutorial? What do you need exactly? – tomislav-maric Jul 7 '12 at 10:10 @tomislav-maric turns out my vocabulary was missing the word baffle... in that case the solution involves calling createBaffles instead of subsetMesh – kar Jul 9 '12 at 7:28

I think what you're looking for is the createBaffles utility:

Use topoSet to create a faceZone, then run something like

createBaffles nameOfFaceZone '(nameOfMasterPatch nameOfSlavePatch)' -overwrite


The patches have to exist already, for which createPatches can come in handy.

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Could you elaborate? – Geoff Oxberry Jul 7 '12 at 15:58
I think the question was more one about nomenclature. The information kar was missing was the name of the utility (or that the OF-developers call the structure he wanted baffles). He seemed rather competent, so he probably already found the missing puzzle pieces at cfd-online.com/Forums/search.php?searchid=1258148&pp=25 – bgschaid Jul 8 '12 at 20:50
One more note: similar questions about OpenFOAM have been closed (with good reason I think) as being "too program specific for a general audience" (quoting from memory) – bgschaid Jul 8 '12 at 20:53
@GeoffOxberry I edited in a slight elaboration. #bgschaid Thanks, that's what I was looking for. Your search link is no longer valid, I found this example though. – kar Jul 9 '12 at 7:22
@GeoffOxberry: OK. Did so: meta.scicomp.stackexchange.com/questions/298/… (noticed that you answered a "symmetrical" question) – bgschaid Jul 11 '12 at 11:49