[GAMBIT] Surface Meshing Issues in Gambit

Forrest · March 26, 2009, 11:04

I have a pipe with a square hole (cut out of the pipes side) that I would like to mesh in Gambit. I have simplified the problem by using the symmetry of the domain. I have three volumes that will eventually be meshed: (1) the interior volume of the pipe, (2) the volume of the hole, and (3) the volume around the pipe. I have already successfully meshed the volume of the hole in the pipe as seen in Image 1 (the orange mesh in the photos). I am trying to mesh the shaded face in Image 2. I want to use hexahedral elements with the map scheme on this face, but Gambit says that the face is not a mapable region and uses the submap scheme to generate the mesh shown in Image 3. I want a nice non-skewed mesh because I'm going to use the Cooper scheme to mesh the outer volume. Is it the inner mesh that messing up my face mesh? Is there anyway that I can fix this or is there a better approach to meshing my domain than splitting it into three volumes and meshing each one separately? Thanks in advance!

-mAx- · March 26, 2009, 13:49

decompose the shaded surface in 2 surfaces (with revolution around the axis).
One surface will be beyond the orange mesh
One surface will be below the orange surface
The last surface will be the "projection" of the orange mesh.
I hope you will understand

Anyway the you should be able ton have 3 nice mappable surface meshes

Forrest · March 26, 2009, 14:57

Ok, I was able to split the surface (using the split surface command with virtual edges). After trying to mesh these new faces, I found that I need to modify my edge meshes so that they have even numbers of intervals. I didn't do anything with the orange mesh since I assume that Gambit will connect the outer volume mesh with the orange one. Was the way I did it what you had in mind MAX?

-mAx- · March 27, 2009, 00:53

hmm... did you already created the edges for splitting? because on the pictures I didn't see any edges for the split I mean.
On the second picture I only see the possibility to split the surface with vertices (On the left side , it seems to be 3 vertices which are symetric to the one on your orange mesh).
If you see what I mean, try to split the shadded surface with a pair of two opposite vertices. I will generates a semi-circle. If it's ok, do the same for creating the 2 next curves.

Forrest · March 27, 2009, 14:22

Thanks max! What you suggested worked great. I was able to split the original shaded region into three new faces and after some finagling I was able to mesh it using quad/map (as you can see below). I had to remove the orange volume mesh to get the edge mesh back for gambit to be happy, but it went back together nicely. Thanks again.

March 26, 2009, 11:04	Surface Meshing Issues in Gambit	#1
Forrest Member Join Date: Mar 2009 Location: Texas Posts: 33 Rep Power: 17	I have a pipe with a square hole (cut out of the pipes side) that I would like to mesh in Gambit. I have simplified the problem by using the symmetry of the domain. I have three volumes that will eventually be meshed: (1) the interior volume of the pipe, (2) the volume of the hole, and (3) the volume around the pipe. I have already successfully meshed the volume of the hole in the pipe as seen in Image 1 (the orange mesh in the photos). I am trying to mesh the shaded face in Image 2. I want to use hexahedral elements with the map scheme on this face, but Gambit says that the face is not a mapable region and uses the submap scheme to generate the mesh shown in Image 3. I want a nice non-skewed mesh because I'm going to use the Cooper scheme to mesh the outer volume. Is it the inner mesh that messing up my face mesh? Is there anyway that I can fix this or is there a better approach to meshing my domain than splitting it into three volumes and meshing each one separately? Thanks in advance!

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March 26, 2009, 13:49		#2
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	decompose the shaded surface in 2 surfaces (with revolution around the axis). One surface will be beyond the orange mesh One surface will be below the orange surface The last surface will be the "projection" of the orange mesh. I hope you will understand Anyway the you should be able ton have 3 nice mappable surface meshes

March 26, 2009, 14:57		#3
Forrest Member Join Date: Mar 2009 Location: Texas Posts: 33 Rep Power: 17	Ok, I was able to split the surface (using the split surface command with virtual edges). After trying to mesh these new faces, I found that I need to modify my edge meshes so that they have even numbers of intervals. I didn't do anything with the orange mesh since I assume that Gambit will connect the outer volume mesh with the orange one. Was the way I did it what you had in mind MAX?

March 27, 2009, 00:53		#4
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	hmm... did you already created the edges for splitting? because on the pictures I didn't see any edges for the split I mean. On the second picture I only see the possibility to split the surface with vertices (On the left side , it seems to be 3 vertices which are symetric to the one on your orange mesh). If you see what I mean, try to split the shadded surface with a pair of two opposite vertices. I will generates a semi-circle. If it's ok, do the same for creating the 2 next curves.

March 27, 2009, 14:22		#5
Forrest Member Join Date: Mar 2009 Location: Texas Posts: 33 Rep Power: 17	Thanks max! What you suggested worked great. I was able to split the original shaded region into three new faces and after some finagling I was able to mesh it using quad/map (as you can see below). I had to remove the orange volume mesh to get the edge mesh back for gambit to be happy, but it went back together nicely. Thanks again.