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August 21, 2015, 09:14 |
Negative Volume
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#1 |
Senior Member
Aja
Join Date: Nov 2013
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Hi dear friends
I have a question about Gambit as follow: I am meshing a turbine. Please see the following dbs file of Gambit: http://www.4shared.com/rar/C-pAhwRlba/max.html I have used boundary layer mesh on the walls. But The mesh is not created in volume 10. In other words, the negative volume is created. Why? I am grateful that guide me. Thanks, Best, Aja |
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August 25, 2015, 02:46 |
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#2 |
Super Moderator
Maxime Perelli
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no problem to mesh your volume 10 from my side
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August 25, 2015, 02:59 |
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#3 |
Senior Member
Aja
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Yes max,
I change default of Gambit as follow: Edit>default>mesh>volume>Use_3D_boundary_layers I changed it to 0 and the volume 10 is meshed. But with change, BL is not created well on the edge. 36 .Please see the following figure. How to solve it? I am grateful that guide me about these subjects. Thanks, Best, Aja |
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August 25, 2015, 03:07 |
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#4 |
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Aja
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of course, My mean is the following file in this thread:
http://www.4shared.com/zip/RpSi4fHhce/max.html Thanks, |
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August 25, 2015, 03:42 |
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#5 |
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Maxime Perelli
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try to split surface in those areas for perturbing the topoloy. And recreate the BL.
You have lots of BL which are not on walls, why are you doing that? Look also at the vertex.176 you have 2 BL which meet the good BL (surrounding your foil) The same at vertex.174
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August 25, 2015, 04:22 |
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#6 | ||
Senior Member
Aja
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Quote:
In case of vertex 176: Which files do you explain? dbs file of this thread is different. I had linked neighboring surfaces of the turbine for imposing periodic boundary conditions in the tangential direction. In fact, periodical boundary conditions are imposed on the neighboring surfaces of the turbine. I had to create lots of BL until Skewness is not appeared in these surfaces. But now, I am using two interface and again in fluent, I do the following works as follow: Define> grid interface>... So I dont need to link these surfaces. Quote:
Thanks, |
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August 25, 2015, 04:48 |
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#7 |
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Maxime Perelli
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sorry
disturbing in areas where you think the BL isn't proper. Sometime if your surface is quite long , there could be problem. If you split your long surface into smaller surfaces, it could help
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August 25, 2015, 05:15 |
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#8 | |
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Aja
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Quote:
But in edge 36 of face 113(please see #4), the face 113 is not long surface. Do you say that I also split this face? According to your explanation, Should I create the new volumes?or just creating the new faces is enough? |
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August 25, 2015, 08:25 |
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#9 |
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Maxime Perelli
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edge36 doesn't belong to surface 113
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August 25, 2015, 08:59 |
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#10 |
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Aja
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How do you understand that edge36 doesn't belong to surface 113?
But when I click on the edge 36, I think that this edge belong to surface 113! Max, In this thread, I am saying about file of post 4 not a file is sent in private massage for you. I am grateful that guide me more about these subjects. thanks, |
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August 26, 2015, 01:11 |
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#11 |
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Maxime Perelli
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Command> face summarize "face.113"
----------------------------------------------------------------- Face: face.113 ----------------------------------------------------------------- Scheme: Map Interval Size: 1.000000 Interval Count: 10 Meshed: Yes Total mesh nodes: 4331 Total mesh faces: 4200 Total Edges: 4 Name Meshed: Vertex_1 Type Vertex_2 Type -------------- ------- -------- ---- -------- ---- edge.248 Yes vertex.269 END vertex.267 END edge.260 Yes vertex.275 END vertex.269 END edge.259 Yes vertex.275 END vertex.274 END edge.257 Yes vertex.267 END vertex.274 END Face used by the following 2 volume(s): volume.19 volume.27 Centroid: ( 0.002559, 0.486907, -0.246806) Coord Sys: c_sys.1 Bounding Box Min: ( -0.057487, 0.486907, -0.298750) Coord Sys: c_sys.1 Bounding Box Max: ( 0.062500, 0.486907, -0.189984) Coord Sys: c_sys.1 Area: 0.011972
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August 26, 2015, 02:31 |
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#12 | |
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Aja
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Hi max,
I removed some BL according to your explanation. But again negative volume is created(in volume 44). I am grateful that see the following file: http://www.4shared.com/zip/N7-j56_xb...ormance-N.html I am grateful that guide me more about this problem. why the negative volume is created in this case? I performed many attempts in order to create real volume but is not created! What do I do? Quote:
Thanks, Best, |
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August 26, 2015, 03:05 |
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#13 |
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Maxime Perelli
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check the picture
Untitled.jpg
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August 26, 2015, 03:25 |
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#14 | |
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Aja
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Quote:
Hi max, Thanks your answer. I had performed this work and The negative volume is created in volume 10 in the following work. please see the following dbs file, Perhaps I am wrong. http://www.4shared.com/zip/GVe275Aiba/max.html even those splits should be normal to the body? |
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August 26, 2015, 03:34 |
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#15 |
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Maxime Perelli
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keep only the BL around your body (and use suface not edge)
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August 26, 2015, 03:50 |
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#16 |
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Aja
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August 26, 2015, 05:15 |
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#17 |
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Aja
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I constructed a new model and performed your explanation, But again the negative volume is created. please check the following dbs file:
http://www.4shared.com/zip/Bngok1a8c...mance-New.html Really I don't know what to do until this problem is solved. Thanks, |
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August 26, 2015, 05:31 |
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#18 |
Super Moderator
Maxime Perelli
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check if you problem comes really from your BL and not from your topology.
For that delete your BL, delete your volume mesh, and remesh (without BL)
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August 26, 2015, 05:41 |
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#19 | |
Senior Member
Aja
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Quote:
This work performed(without BL), But again the negative volume is created! What is your exact meaning of "topology"? |
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August 26, 2015, 05:43 |
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#20 |
Super Moderator
Maxime Perelli
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post a screenshot of your mesh
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In memory of my friend Hervé: CFD engineer & freerider |
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