CFD Online Discussion Forums

CFD Online Discussion Forums (
-   OpenFOAM Mesh Utilities (
-   -   SnappyHexMesh generates 8823 patches (

cricke October 8, 2008 02:44

I have created a background me
I have created a background mesh in blockMesh and imported a STL cube from blender. The final mesh locks ok but i generates 8823 patches, all with the same amount of faces and startFace. The are named cube_patch0, cube_patch1 etc...Anyone having a clue what is wrong. I have only defined one single patch in snappyHexMesh.

mattijs October 8, 2008 03:33

You'll get a patch for every '
You'll get a patch for every 'solid' (region) in an stl.

Maybe you can specify inside Blender to put all in single solid? Or if your stl is in ascii format you can open it with a text editor and remove all unnecessary solids. If it is binary go back into Blender and save as ascii - binary does not support different regions.

olesen October 8, 2008 04:25

Since blender cannot export as
Since blender cannot export ascii STL, I suggest you try exporting as wavefront .obj format (which OpenFOAM can also read). This is not only slightly more memory efficient (since you don't have duplicated points everywhere), but is also easy to modify. Even if you accidentally export various groups, modifying the resulting .obj file is trivial. Eg, to remove all groups:
$ sed -ne '/^g/!p' orig.obj > new.obj

Note 1:
If you re-import .obj files into blender, make sure that you have 'clamping' turned off to avoid automatically rescaling your geometry. I hacked the python script to have it always turned off.

Note 2:
When working in blender, you might wish to use the Ctrl-N key (or Windows-N key) to activate the "Transform Properties" popup. You can then lock down all the parameters to avoid accidentally moving or resizing the object. The behaviour of the nodes edit and sculpt modes are unaffected.

cricke October 8, 2008 08:30

I sold it using the following
I sold it using the following thread. Tahnks

search title in forum:

"Blender export script for named ASCII STL's "

raptor3x November 14, 2008 17:28

I've tried using a wavefront .
I've tried using a wavefront .obj file instead of an .stl file and while snappy seems to read it fine, it also seems to completely ignore it. Is there a special switch that needs to be used?

All times are GMT -4. The time now is 19:05.