Problem extruding Boundary Mesh

Curro5150 · January 23, 2014, 17:09

Hello,

I don't know if there is something wrong with my geometry or if this is a bug in engrid, but I have been trying to create a mesh around a simple strut, and when I extrude the boundary layer some points do not get extruded and/or the boundary layer mesh shows "holes" in it. I think that this is causing NETGEN to crash if I try to continue with the process. Has anybody else experienced this problem? Is there an easy solution?

Thank you,

Francisco

wyldckat · January 24, 2014, 19:08

Greetings Francisco,

Can you share any images of the problematic locations? Because from the description you've given, I'm not managing to picture it in my mind

Best regards,
Bruno

Curro5150 · January 24, 2014, 21:56

These are a few pictures of the BL mesh and the surface below it. Thanks

wyldckat · January 25, 2014, 08:42

Hi Francisco,

The fourth image is showing some reasons of concern about the surface mesh. The triangles on the right are very thin and that darker part of the mesh, where it seems to sink into the volume, is a very big reason of concern.

A few questions:

Is that darker region implying that there are some surfaces that are not being meshed?
Are you keeping each curved and flat surfaces on their own boundary code, or are you leaving them together in a single item?
When the boundary layer finished, does it give any warning or error messages?

Best regards,
Bruno

Curro5150 · January 25, 2014, 09:26

Hi Bruno,

The darker region is the part in which the BL mesh is not being extruded properly. It shows as a "hole" and that is why it looks darker. Right now, every surface on the strut has their own boundary code, with the leading edge separated into another so that it can be assigned a finer mesh. I have found that this also prevents the smoother to do funny things because of the change in curvature. No error messages appeared. I was having problems with overlapping faces, but those are solved now.

Thanks,

Francisco

wyldckat · January 25, 2014, 11:37

Hi Francisco,

On that problem location, what does the original geometry look like?

Best regards,
Bruno

Curro5150 · January 25, 2014, 12:03

Hi,

This is how the blender import looks like. It is like this for the whole leading edge.

Thanks for the help,

Francisco

wyldckat · January 26, 2014, 06:03

Hi Francisco,

Are you sure that is the right image/location? I was asking about the original geometry on the location for the 4th image, namely this one:

If it is the correct location, do you have at least 3 boundary codes for describing this region? On on the top, another on the bottom and another for the curved edge.

Best regards,
Bruno

pirsquared · January 26, 2014, 20:58

[post deleted]

taxalian · March 23, 2014, 04:07

Quote:

Originally Posted by pirsquared

[post deleted]

Hi Richard,
Prism layers generated without any problem. See the file showing the boundary layer mesh over the sphere.

January 23, 2014, 17:09	Problem extruding Boundary Mesh	#1
Curro5150 New Member Francisco Miguel Join Date: Apr 2010 Posts: 13 Rep Power: 16	Hello, I don't know if there is something wrong with my geometry or if this is a bug in engrid, but I have been trying to create a mesh around a simple strut, and when I extrude the boundary layer some points do not get extruded and/or the boundary layer mesh shows "holes" in it. I think that this is causing NETGEN to crash if I try to continue with the process. Has anybody else experienced this problem? Is there an easy solution? Thank you, Francisco

January 24, 2014, 19:08		#2
wyldckat Retired Super Moderator Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,974 Blog Entries: 45 Rep Power: 128	Greetings Francisco, Can you share any images of the problematic locations? Because from the description you've given, I'm not managing to picture it in my mind Best regards, Bruno __________________ OpenFOAM: FAQ \| Getting started Forum: How to get help, to post code/output and forum guide Read this before sending me PM

January 25, 2014, 08:42		#4
wyldckat Retired Super Moderator Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,974 Blog Entries: 45 Rep Power: 128	Hi Francisco, The fourth image is showing some reasons of concern about the surface mesh. The triangles on the right are very thin and that darker part of the mesh, where it seems to sink into the volume, is a very big reason of concern. A few questions: Is that darker region implying that there are some surfaces that are not being meshed? Are you keeping each curved and flat surfaces on their own boundary code, or are you leaving them together in a single item? When the boundary layer finished, does it give any warning or error messages? Best regards, Bruno

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January 25, 2014, 09:26		#5
Curro5150 New Member Francisco Miguel Join Date: Apr 2010 Posts: 13 Rep Power: 16	Hi Bruno, The darker region is the part in which the BL mesh is not being extruded properly. It shows as a "hole" and that is why it looks darker. Right now, every surface on the strut has their own boundary code, with the leading edge separated into another so that it can be assigned a finer mesh. I have found that this also prevents the smoother to do funny things because of the change in curvature. No error messages appeared. I was having problems with overlapping faces, but those are solved now. Thanks, Francisco

January 25, 2014, 11:37		#6
wyldckat Retired Super Moderator Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,974 Blog Entries: 45 Rep Power: 128	Hi Francisco, On that problem location, what does the original geometry look like? Best regards, Bruno

January 26, 2014, 06:03		#8
wyldckat Retired Super Moderator Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,974 Blog Entries: 45 Rep Power: 128	Hi Francisco, Are you sure that is the right image/location? I was asking about the original geometry on the location for the 4th image, namely this one: If it is the correct location, do you have at least 3 boundary codes for describing this region? On on the top, another on the bottom and another for the curved edge. Best regards, Bruno