Negative Volume
 

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

no problem to mesh your volume 10 from my side

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?

http://0up.ir/do.php?imgf=Capture66.jpg

I am grateful that guide me about these subjects.

Thanks,

Best,

Aja

of course, My mean is the following file in this thread:

http://www.4shared.com/zip/RpSi4fHhce/max.html

Thanks,

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

what is your exact meaning of 'perturbing'? Which areas? I am grateful that guide me more.



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.

totally, I have to create BL in some part, Is there any problem?


Thanks,

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

Ok, you are right,

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?

edge36 doesn't belong to surface 113

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,

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

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?

Your explanation is not about dbs file of this thread.




Thanks,

Best,

check the picture
Attachment 41645

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?

keep only the BL around your body (and use suface not edge)

I perform your explanations, If again I had the problem, I post here.

Thanks

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,

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)

really thanks,

This work performed(without BL), But again the negative volume is created!

What is your exact meaning of "topology"?

post a screenshot of your mesh