[snappyHexMesh] snappy snaps to bad surface

petr.f. · October 6, 2014, 05:40

Hi all!

I have the following problem with snappyHexMesh: I have to mesh an object with a thin surface. The geometry is closed (and supplied in stl format). Snappy however breaks through the surface it should be snapping to and snaps to the underlying surfaces - please see the pictures. I can help it by setting tolerance to 1.0 but then other parts of the mesh are distorted. I'm using OF2.3.x, where this shouldn't appear at all (due to the new feature detectNearSurfacesSnap).

Any idea what to change in the settings?

wyldckat · October 11, 2014, 13:37

Greetings Petr,

A few questions:

Are you trying to create a multi-region mesh?
How many STL files with how many geometries (closed surfaces) inside each STL file?
How many cells are available in the refined mesh for snapping onto the thin surface? I ask this in particular because of this bug: http://www.openfoam.org/mantisbt/view.php?id=295

Best regards,
Bruno

petr.f. · October 13, 2014, 06:14

Hello Bruno,

thanks a lot for your reply.

The answers to your questions are:
1) Yes I am.
2) In total 13 stl files with many closed surfaces (~ 72).
3) There is quite a lot of cells in the refined mesh. But as you can see from the pictures it's less than in the original stl file.

I'll try to run all the stages separately and let you know.

Best regards, Petr.

wyldckat · October 18, 2014, 15:59

Quick hint: As with most things related to OpenFOAM, you should always start investigating functionalities in OpenFOAM by starting with one or more simpler cases, so that you can isolate one problem at a time

If you read this wiki page: http://openfoamwiki.net/index.php/SnappyHexMesh - you should get that exact feeling as well

October 11, 2014, 13:37		#2
wyldckat Retired Super Moderator Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,981 Blog Entries: 45 Rep Power: 128	Greetings Petr, A few questions: Are you trying to create a multi-region mesh? How many STL files with how many geometries (closed surfaces) inside each STL file? How many cells are available in the refined mesh for snapping onto the thin surface? I ask this in particular because of this bug: http://www.openfoam.org/mantisbt/view.php?id=295 Best regards, Bruno __________________ 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 13, 2014, 06:14		#3
petr.f. Member Petr Furmanek Join Date: Jan 2012 Location: Faenza, Italy Posts: 66 Rep Power: 14	Hello Bruno, thanks a lot for your reply. The answers to your questions are: 1) Yes I am. 2) In total 13 stl files with many closed surfaces (~ 72). 3) There is quite a lot of cells in the refined mesh. But as you can see from the pictures it's less than in the original stl file. I'll try to run all the stages separately and let you know. Best regards, Petr.

October 18, 2014, 15:59		#4
wyldckat Retired Super Moderator Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,981 Blog Entries: 45 Rep Power: 128	Quick hint: As with most things related to OpenFOAM, you should always start investigating functionalities in OpenFOAM by starting with one or more simpler cases, so that you can isolate one problem at a time If you read this wiki page: http://openfoamwiki.net/index.php/SnappyHexMesh - you should get that exact feeling as well