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Nolwenn March 17, 2011 10:34

Snappy: cell normal orientation on open surface
Hello everybody,

When i use snappyHexMesh on a surface which isn't a closed one I have a problem with cell normals orientation: it isn't uniform on the surface (kind of random between 1 or -1). Normals are well oriented on my .stl file.

Do you know a way to harmonize cell normals orientation after meshing ?

Or maybe SnappyHexMesh isn't confortable with open surface?

andrea.pasquali August 25, 2011 16:39

Hi Nolwenn,
I have the same problem, I'd like to have uniform cellNormal in some faceZones inside my volume.
I tried renumberMesh but without complete success.
Did you found a solution for your problem?


Nolwenn August 26, 2011 03:08

Hello Andrea,

No, for the moment I didn't make any progress with this.
Can you tell me if you find something interesting ?



andrea.pasquali August 26, 2011 03:16

1 Attachment(s)
You can see my problem in attached picture,
I'd like to calculate the mass flow rater throgh a faceZone.
The problem is the cellNormal in Z direction are random! (In my starting .stl the normals are uniform).
So if I calculate the mass flow rate with OF function sum(phi) I got error.
I'm thinking to calculate it like sum(phi*sign(normal)).
Do you know if the normal is exportable like a field? I can see it in paraview but I don't see anything in my time or constant directory (I think paraview elaborate it depending on nodes numbering)


StSchiff June 29, 2012 06:20

I have the same problem. Did you ever find out how to reset the surface normals?

Nolwenn July 5, 2012 04:40

Nothing new ... I extract the values from neighbours cells during post processing.


prodo June 3, 2015 04:54

Also, I have same problem.

So, Does anyone know how to use surfaceOrient utility?

prodo June 4, 2015 08:41

I solved this problem from surfaceOrient utility
surfaceOrient <surfaceFile> <visiblePoint> <output surface file>

prodo June 4, 2015 08:46

I solved this problem from surfaceOrient utility

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