[surface handling] Problem getting the complete patches using SurfaceToPatch

vineet_bhola · August 11, 2015, 05:53

Hi All,
I have to smulate heat transfer between air to a solid to water. Please refer to the attachment cfd_summary. Cylinder colored red is hot air, white casing is solid and then blue as water.
Currently i am meshing only water and solid. I have created the mesh successfully but I am was unable to get patches from stl surface directly after snappyhexmesh.(please refer to the compressed file for scripts) It was showing 0 faces for all the patches except defaultFaces. So i used surfaceToPatch after it using the combined water and solid stl data.
Problem with that is it does not extract the complete patch, some of the triangular faces are not attributed to inlet and outlet. Compare the attachment of wasser_zoom versus wasser_stl
Does anyone know the reason behind this error. Which parameters or tolerances can I vary for surfaceToPatch command.
Thanks
Vineet

vineet_bhola · August 11, 2015, 05:57

Just to avoid any confusion. Red circle in "Wasser_stl" is not hot air. That was the default color of stl geometry. It is just to compare, what I need and what I actually got as an nlet patch

vineet_bhola · August 12, 2015, 04:40

Has no one worked with surfaceToPatch before?

vineet_bhola · August 18, 2015, 09:54

I don't know the exact Background process. But by hit and Trial I found out that by changing tolerance Option in surfaceToPatch, these missing faces can be regained..For example, when I used .01 as tolerance, it showed 79 missing faces but with 0.0005 it showed 0...beware that if you Keep tolerance too low, it can shift all the faces to Defaultpatch OR OldinternalFaces...
By Default the tolerance is 0.001 OR 1.0 e-3

August 18, 2015, 09:54		#4
vineet_bhola Member Vineet Bhola Join Date: Jun 2015 Location: Chemnitz, Germany Posts: 49 Rep Power: 10	I don't know the exact Background process. But by hit and Trial I found out that by changing tolerance Option in surfaceToPatch, these missing faces can be regained..For example, when I used .01 as tolerance, it showed 79 missing faces but with 0.0005 it showed 0...beware that if you Keep tolerance too low, it can shift all the faces to Defaultpatch OR OldinternalFaces... By Default the tolerance is 0.001 OR 1.0 e-3 peppino likes this.

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August 11, 2015, 05:57		#2
vineet_bhola Member Vineet Bhola Join Date: Jun 2015 Location: Chemnitz, Germany Posts: 49 Rep Power: 10	Just to avoid any confusion. Red circle in "Wasser_stl" is not hot air. That was the default color of stl geometry. It is just to compare, what I need and what I actually got as an nlet patch

August 12, 2015, 04:40		#3
vineet_bhola Member Vineet Bhola Join Date: Jun 2015 Location: Chemnitz, Germany Posts: 49 Rep Power: 10	Has no one worked with surfaceToPatch before?