Strange STL when using cuttingPlane

C-L · September 25, 2017, 08:32

Hi all,

I'm trying to use cuttingPlanes to visualise my results but the creation of the surface file seems very strange (see the attached image). The geometry of the mesh is captured fine but there are lots of strange cells scattered on the nearest mesh boundary. Has anyone seen this before?

Attachment 58616

There aren't many options for creating the cuttingPlane but I have tried changing the surface format from stl to vtk with no difference. I have also tried keeping the data as a foamFile but I'm not sure how to visualise this.

I have also tried using a standard plane instead of a cutting plane; this removes the strange 'dotted' surfaces but some of the cells seem to be missing from the surface (also attached - the missing ones are the squares)!

Attachment 58617

Let me know if you have any other suggestions!

Charlie

C-L · September 25, 2017, 08:41

Forgot to attached the cuttingPlane script:

cuttingPlane
{
type surfaces;
libs ("libsampling.so");
writeControl writeTime;
surfaceFormat stl;
fields ( );// p U vorticity Q grad(U) mag(grad(U)) );
interpolationScheme cellPoint;

surfaces
(
xNormal0{type plane; normalVector (1 0 0); basePoint (0.87 0 0); interpolate false;}
// xNormal1{type cuttingPlane; planeType pointAndNormal; pointAndNormalDict{basePoint (0.925 0 0); normalVector (1 0 0);} interpolate true;}
);
}

C-L · September 26, 2017, 05:44

An update ..

I have been creating these cut planes using paraview instead and I have found that I can remove the problem if I decompose the mesh into tets. The below image is the non-decomposed mesh with a slice which gives me the same gaps in the surface as the openfoam cuttingPlane utility.

non-decomposed.png

If I turn on crinkle cut you can clearly see that this gap is not a feature of the mesh (below image).

non-decomposed-crinkleSlice.png

The issue only goes away when I decompose the mesh into tets and then create the slice (see below).

decomposed.png

HOWEVER - I would like to avoid decomposing the mesh in order to save memory since I will be creating many of these vtk files. Has anyone come across this issue before?

September 25, 2017, 08:32	Strange STL when using cuttingPlane	#1
C-L Member Charlie Lloyd Join Date: Feb 2016 Posts: 57 Rep Power: 10	Hi all, I'm trying to use cuttingPlanes to visualise my results but the creation of the surface file seems very strange (see the attached image). The geometry of the mesh is captured fine but there are lots of strange cells scattered on the nearest mesh boundary. Has anyone seen this before? Attachment 58616 There aren't many options for creating the cuttingPlane but I have tried changing the surface format from stl to vtk with no difference. I have also tried keeping the data as a foamFile but I'm not sure how to visualise this. I have also tried using a standard plane instead of a cutting plane; this removes the strange 'dotted' surfaces but some of the cells seem to be missing from the surface (also attached - the missing ones are the squares)! Attachment 58617 Let me know if you have any other suggestions! Charlie

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
[snappyHexMesh] What CAD software do you use to define STL surfaces?	Awak	OpenFOAM Meshing & Mesh Conversion	11	November 12, 2020 11:00
[CAD formats] Creating waterproof STL using snappyHexMesh or salome	Tobi	OpenFOAM Meshing & Mesh Conversion	58	May 13, 2020 06:01
[ICEM] STL file! How is it useful?	bidi	ANSYS Meshing & Geometry	0	December 26, 2016 21:33
[ICEM] Work with imported STL geometry	KateEisenhower	ANSYS Meshing & Geometry	2	July 9, 2015 10:46
[snappyHexMesh] Experimentally obtained STL file for internal Flow SnappyHexMesh	Irish09	OpenFOAM Meshing & Mesh Conversion	9	April 7, 2012 08:50

September 25, 2017, 08:41		#2
C-L Member Charlie Lloyd Join Date: Feb 2016 Posts: 57 Rep Power: 10	Forgot to attached the cuttingPlane script: cuttingPlane { type surfaces; libs ("libsampling.so"); writeControl writeTime; surfaceFormat stl; fields ( );// p U vorticity Q grad(U) mag(grad(U)) ); interpolationScheme cellPoint; surfaces ( xNormal0{type plane; normalVector (1 0 0); basePoint (0.87 0 0); interpolate false;} // xNormal1{type cuttingPlane; planeType pointAndNormal; pointAndNormalDict{basePoint (0.925 0 0); normalVector (1 0 0);} interpolate true;} ); }

September 26, 2017, 05:44		#3
C-L Member Charlie Lloyd Join Date: Feb 2016 Posts: 57 Rep Power: 10	An update .. I have been creating these cut planes using paraview instead and I have found that I can remove the problem if I decompose the mesh into tets. The below image is the non-decomposed mesh with a slice which gives me the same gaps in the surface as the openfoam cuttingPlane utility. non-decomposed.png If I turn on crinkle cut you can clearly see that this gap is not a feature of the mesh (below image). non-decomposed-crinkleSlice.png The issue only goes away when I decompose the mesh into tets and then create the slice (see below). decomposed.png HOWEVER - I would like to avoid decomposing the mesh in order to save memory since I will be creating many of these vtk files. Has anyone come across this issue before?