Unable to import mesh - identify problematic face

TWA · April 17, 2014, 07:01

Hi,

I'm importing a large mesh containing several bodies into CFX-Pre. The mesh is made in ANSYS Meshing (Workbench, ANSYS 15). Pre starts to load the mesh, but upon completing, i get the error message as seen in the attachment.

The mesh has (should have?) matching connections, i.e. the mesh is continuous throughout the bodies. But the error message indicate that there may be a face where this is not true and the mesh is bad. Problem is that since the mesh will not load in Pre, how do I identify this face (F434.x) given in the error message?

The mesh contains hundreds of faces, so I cant check them all manually. But I have checked the mesh at certain "high risk" locations without observing anything out of the ordinary.

mvoss · April 17, 2014, 09:47

Maybe you can disable the automatic interface creation for the mesh to load at least.

TWA · April 17, 2014, 09:58

Yes, already tried that. The same error message appears :/ (Disabled both in the import mesh window and in the general case options)

mvoss · April 17, 2014, 10:01

Did you try to find the vertex 202 instead of the the face 4**?

TWA · April 19, 2014, 10:50

I don't really know how to find that either...

But at least I have some progress. By suppressing several bodies and using trial and error, I've identified the face in the error message. I've also discovered that there are a few more faces in the mesh which produce the same error

Now I have to see if I am able to fix the first one...

TWA · April 29, 2014, 08:52

When I tried to construct the mesh in 14.5, it was successfully imported to CFX Pre 15, so I suspected this to be a bug. I got this confirmed by Ansys today:

Quote:

Yes, this is a reported bug. It is fixed till next release, R16. So, unfortunately you need to use the previous version 14.5.7.

I'm sorry for any inconvenience.

Regards
Tomas

Thank you,
ANSYS Technical Support

singer1812 · April 29, 2014, 10:03

Im not a big WB Mesher for CFD user, but this seems incredible!

Can you explain exactly what the bug was? Is Pre unable to import Multi-Body Meshes from WB? And no fix till 16 seems unreasonable for a problem you describe. Was there no other work around? Did you get past tier 1 support?

TWA · May 2, 2014, 03:49

Quote:

Originally Posted by singer1812

Im not a big WB Mesher for CFD user, but this seems incredible!

Can you explain exactly what the bug was? Is Pre unable to import Multi-Body Meshes from WB? And no fix till 16 seems unreasonable for a problem you describe. Was there no other work around? Did you get past tier 1 support?

The problem was that 1:1 mesh was not fulfilled on some mesh interfaces. The bug is probably in the mesh program. I don't know why the problem occurs on just a few interfaces... I was able to import multi-body mesh with 1:1 mesh when I suppressed several "problematic" bodies, so the problem is not general.

When constructing the mesh in Ansys 14.5 (with exactly the same geometry input and settings), it worked fine to import it in Pre 15.

What is tier 1 support?

singer1812 · May 2, 2014, 09:46

Tier 1 support is the guy you first talk to. Usually it is a general support engineer and not the developers. I have found that sometimes (for harder problems) the support engineers write off things as unworkable, or propose an ineligant solution, that a developer would correct.

Now that you have described the problem a bit more, I have seen the meshing issue that you describe (at 14.5 and prior). I have even seen the opposite where I want 2 distinct bodies with a 1:1 continuous mesh connect between them and the WB mesher will import the geometry as 1 body (even though it is 2 bodies in DM).

I have found that it usually means the body is badly built in DM. To fix it, I usually build up the offending body again from scratch, in a slightly different way, and the problem in the mesher goes away.

TWA · May 7, 2014, 03:51

Ok, I used the "Siebel eCustomer Portal 8.1" on the Ansys Customer Portal.

Yes, after a few years working with this software, I too have experienced problems such as you describe. I tried to re-model the problematic bodies, but it didn't help.

This is the first time I have experienced problems when importing a seemingly good mesh into Pre, and that's why I suspected it to be a bug rather than a dirty geometry. With dirty geometries, the problems always appear when importing the geometry into the meshing software, or during the meshing itself. At least that's my experience

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April 17, 2014, 09:47		#2
mvoss Senior Member Matthias Voß Join Date: Mar 2009 Location: Berlin, Germany Posts: 449 Rep Power: 20	Maybe you can disable the automatic interface creation for the mesh to load at least.

April 17, 2014, 09:58		#3
TWA New Member Join Date: Sep 2011 Location: Norway Posts: 11 Rep Power: 15	Yes, already tried that. The same error message appears :/ (Disabled both in the import mesh window and in the general case options)

April 17, 2014, 10:01		#4
mvoss Senior Member Matthias Voß Join Date: Mar 2009 Location: Berlin, Germany Posts: 449 Rep Power: 20	Did you try to find the vertex 202 instead of the the face 4**?

April 19, 2014, 10:50		#5
TWA New Member Join Date: Sep 2011 Location: Norway Posts: 11 Rep Power: 15	I don't really know how to find that either... But at least I have some progress. By suppressing several bodies and using trial and error, I've identified the face in the error message. I've also discovered that there are a few more faces in the mesh which produce the same error Now I have to see if I am able to fix the first one...

April 29, 2014, 10:03		#7
singer1812 Senior Member Edmund Singer P.E. Join Date: Aug 2010 Location: Minneapolis, MN Posts: 511 Rep Power: 21	Im not a big WB Mesher for CFD user, but this seems incredible! Can you explain exactly what the bug was? Is Pre unable to import Multi-Body Meshes from WB? And no fix till 16 seems unreasonable for a problem you describe. Was there no other work around? Did you get past tier 1 support?

May 2, 2014, 09:46		#9
singer1812 Senior Member Edmund Singer P.E. Join Date: Aug 2010 Location: Minneapolis, MN Posts: 511 Rep Power: 21	Tier 1 support is the guy you first talk to. Usually it is a general support engineer and not the developers. I have found that sometimes (for harder problems) the support engineers write off things as unworkable, or propose an ineligant solution, that a developer would correct. Now that you have described the problem a bit more, I have seen the meshing issue that you describe (at 14.5 and prior). I have even seen the opposite where I want 2 distinct bodies with a 1:1 continuous mesh connect between them and the WB mesher will import the geometry as 1 body (even though it is 2 bodies in DM). I have found that it usually means the body is badly built in DM. To fix it, I usually build up the offending body again from scratch, in a slightly different way, and the problem in the mesher goes away.

May 7, 2014, 03:51		#10
TWA New Member Join Date: Sep 2011 Location: Norway Posts: 11 Rep Power: 15	Ok, I used the "Siebel eCustomer Portal 8.1" on the Ansys Customer Portal. Yes, after a few years working with this software, I too have experienced problems such as you describe. I tried to re-model the problematic bodies, but it didn't help. This is the first time I have experienced problems when importing a seemingly good mesh into Pre, and that's why I suspected it to be a bug rather than a dirty geometry. With dirty geometries, the problems always appear when importing the geometry into the meshing software, or during the meshing itself. At least that's my experience