Triangles are degenerate Pointwise

pcm · July 11, 2017, 07:21

Hello,

I'm trying to initialise a block and at first I had intersecting triangles because the equiarea skewness of some cells was too high. However, after fixing this problem the block can't still be initialised and I get the message "Triangles are degenerate".

Can anyone help? Thanks

rmatus · July 11, 2017, 12:28

Will need some more information to help with this. Can you share your Pointwise project file. If you can't share the project file, can you post some pictures of the problem area and cut and past the full error messages from Pointwise?

What is your maximum equiarea skewness now? How did you make the surface mesh, e.g. isotropic or T-Rex, all triangles or mixed quads and tris, etc?

Rick

pcm · July 11, 2017, 12:40

My surface mesh is an unstructured one (just triangles). I can't post pictures right now, but I can tell you that my maximum equiarea skewness is now below 0.7. Do you think I should try to decrease it even more?

Just some more info until I post some pictures, what I'm trying to do is initialise a block between an inner cylinder and an outer cylinder (this one is an annular cylinder, of course).

rmatus · July 11, 2017, 13:55

Skewness below 0.7 everywhere should be fine.

How large are the surface triangles compared to the size of the gap between the inner and outer cylinders?

How was the block constructed? Does it have two faces with the inner cylinder as one face and the outer cylinder as the other face?

Rick

pcm · July 13, 2017, 11:08

I solved the problem and I'll post it just in case someone else needs it.

When getting the triangles are degenerate error, you get the coordinates of the points of the triangle that it is causing that error. One way to solve this problem is locating this triangle and smoothing the surface mesh around that area.

July 11, 2017, 07:21	Triangles are degenerate Pointwise	#1
pcm New Member Join Date: May 2017 Posts: 6 Rep Power: 8	Hello, I'm trying to initialise a block and at first I had intersecting triangles because the equiarea skewness of some cells was too high. However, after fixing this problem the block can't still be initialised and I get the message "Triangles are degenerate". Can anyone help? Thanks

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July 11, 2017, 12:28		#2
rmatus Senior Member Rick Matus Join Date: Mar 2009 Location: Fort Worth, Texas, USA Posts: 116 Rep Power: 17	Will need some more information to help with this. Can you share your Pointwise project file. If you can't share the project file, can you post some pictures of the problem area and cut and past the full error messages from Pointwise? What is your maximum equiarea skewness now? How did you make the surface mesh, e.g. isotropic or T-Rex, all triangles or mixed quads and tris, etc? Rick

July 11, 2017, 12:40		#3
pcm New Member Join Date: May 2017 Posts: 6 Rep Power: 8	My surface mesh is an unstructured one (just triangles). I can't post pictures right now, but I can tell you that my maximum equiarea skewness is now below 0.7. Do you think I should try to decrease it even more? Just some more info until I post some pictures, what I'm trying to do is initialise a block between an inner cylinder and an outer cylinder (this one is an annular cylinder, of course).

July 11, 2017, 13:55		#4
rmatus Senior Member Rick Matus Join Date: Mar 2009 Location: Fort Worth, Texas, USA Posts: 116 Rep Power: 17	Skewness below 0.7 everywhere should be fine. How large are the surface triangles compared to the size of the gap between the inner and outer cylinders? How was the block constructed? Does it have two faces with the inner cylinder as one face and the outer cylinder as the other face? Rick

July 13, 2017, 11:08		#5
pcm New Member Join Date: May 2017 Posts: 6 Rep Power: 8	I solved the problem and I'll post it just in case someone else needs it. When getting the triangles are degenerate error, you get the coordinates of the points of the triangle that it is causing that error. One way to solve this problem is locating this triangle and smoothing the surface mesh around that area.