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charltonjames August 11, 2009 08:17

Surface is not manifold
Hi, after successfully getting around my free edges problem i have now struck another one when trying to generate a volume mesh. I now get an error stating that the surface is not manifold. I half know what this is, but have no idea what the best solution is to fix this problem. Do you have any suggestions?



vishyaroon August 11, 2009 08:47

Hello Jim,

How many such surfaces do you have? These are because of having more than two surface elements intersecting on a line. If you look into these cells by browsing through the list of surfaces you'll find more than two surface elements (triangles) intersecting on one edge. You may want to delete the unwanted ones.

You can check the surface mesh quality by going into Representations > Surface Mesh. Right click on Surface mesh and select Repair Mesh. This will show you pierced faces, free edges and non-manifold edges and points. It is important to get rid of these 4 surface problems before you proceed with your volume mesh.

charltonjames August 12, 2009 11:41

Hi, thanks for the help. i have editted my model now, and i have no free edges or non-manifold edges!! However, i have 1 non-manifold vertices and a couple hundred pierced faces. As i still cant generate a volume mesh, do i need to fix these first?? If so, what is the best way?? I have tried to click on auto repair within Representations > Surface Mesh > Repair Mesh, but get an error message about sideness.......

Any suggestions???



vishyaroon August 12, 2009 12:14

I guess fixing the non-manifold vertices should be similar to fixing the non-manifold edges.

However with the pierced faces can you check if all these faces are lying in the vicinity of one another. I have encountered the sideness error a bunch of times too. It has helped when I decrease the mesh size locally in the region where the surface error occurs. But I'm not sure if that is the solution for it. I think I should also find out the cause of this problem to see why it occurs and that would tell us what to do to fix it.

Gamer26 September 23, 2010 08:36

Hi everybody.

I am getting the surface is not manifold error message at the beginning of the volume mesh phase. I have tried the repair surface on both my wrapped surface and my remeshed surface. Both have no problems, no non-manifold edges or vertices, free edges, pierced faces etc...

Any ideas?


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