CFD Online Discussion Forums

CFD Online Discussion Forums (
-   OpenFOAM Native Meshers: snappyHexMesh and Others (
-   -   Boundary Patch definition on Thin Surfaces / Internal Walls in SnappyHex (

Hannes_Kiel September 6, 2011 04:47

Boundary Patch definition on Thin Surfaces / Internal Walls in SnappyHex
I'm trying to generate a mesh around a thin surface / internal wall like a sail. Basically, it works fine, the STL surface mesh is found, properly resolved and written out as external faces / boundary patch. My problem is the following: I haven't managed to assign different boundary patch identifiers to the two sides of the surface, both sides are within one patch with associated normals pointing both directions. I cannot separate them by mergeOrSplitBaffles as the nodes of both sides are not identical. When importing two identical STL surfaces meshes with opposed normals, I get two patches, both seriously fragmented. I know that some have just assigned a finite thickness to their geometry when working on similar problems, others (Russo et al) have written additional routines to get around it. I'm trying to avoid both.

Does anybody know whether a) there is a way to either generate a volume mesh around an infinetly thin geometry with both sides in separate boundary patches or b) split the single boundary patch into two along the edges?


StSchiff June 29, 2012 06:18

Hello Hannes,
I have the same problem you had, trying to mesh a surface of zeroThickness, but snappy messes up the surface normals. Did you ever find a workaround the problem?

Hannes_Kiel July 2, 2012 01:55

Hi Stefanie,

I gave up trying as I had to work on other, more pressing, topics and could generate suitable meshes using ICEM. It might be worth a try to see whether enGrid or Salome are capabel of generating such meshes.


StSchiff July 2, 2012 04:22

Hi Hannes,
thanks for your reply, I'll keep trying to get in to work with snappy but maybe also have a look into other meshing tools.

ripudaman August 27, 2013 01:06

Hi Stefanie,

Were you able to figure out a solution to this problem? I am trying to do something similar. I want to split this internal boundary and want to apply different boundary conditions on the two mirror faces.


All times are GMT -4. The time now is 03:19.