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Old   November 17, 2009, 01:21
Default How to delete the wall?
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Dr Suvash C Saha
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Hi,
I am generating mesh for a sphere with an inlet. Therefore, I have to generate two volumes. After generating the mesh I don't want to see the outer surface wall of the inlet volume. How can I remove this wall? If the wall is there what boundary condition I should use so that this wall will not affect the flow. Please help..

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Old   November 17, 2009, 02:05
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Hi Suvash,

u generating the sphere as a solid part?
I will suggest you deactivate the sphere volume by grid>zone>deactivate.

hope this help.
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Old   November 17, 2009, 02:09
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Thanks. Not really. The inner volume is not solid. As you have advised, I went through grid>zone>deactivate. But I cant see volume2 there. Just see 'Fluid'. Should I deactivate it?
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Old   November 17, 2009, 02:12
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u need to break the mesh into 2 pieces in order to deactivate each one of it.
u can use gambit to break it first before u load the mesh into fluent.

if u need the fluid to pass thru each other, u can create sliding interface on the connecting wall.
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Old   November 17, 2009, 02:45
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Quote:
Originally Posted by herntan View Post
u need to break the mesh into 2 pieces in order to deactivate each one of it.
u can use gambit to break it first before u load the mesh into fluent.

if u need the fluid to pass thru each other, u can create sliding interface on the connecting wall.
How to break the mesh into 2 pieces in Gambit? Is there any tutorial in the Gambit documents?

There is not boundary condition in Fluent like sliding interface.

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Old   November 17, 2009, 02:54
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Its hard to break it after u mesh. Its better u do it before u mesh.
U can slice solid into 2 piece using a surface.
Or u can use boolen way, add/substract/intersect 2 piece of solid.

to set up sliding interface.
example : u got part A and part B touching each other. U need to set the touching surface become boundary condition : INTERFACE .
Then when u load it into Fluent, u can use Grid>grid interface , the select the surface at A (which touching B) and couple with surface at B (which touching A).
this 2 touching part will have fluid pass thru each other on the touching surface.

hope this help.
u can refer to sliding mesh in the tutorial too.
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Old   November 24, 2009, 02:27
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Quote:
Originally Posted by herntan View Post
Its hard to break it after u mesh. Its better u do it before u mesh.
U can slice solid into 2 piece using a surface.
Or u can use boolen way, add/substract/intersect 2 piece of solid.

to set up sliding interface.
example : u got part A and part B touching each other. U need to set the touching surface become boundary condition : INTERFACE .
Then when u load it into Fluent, u can use Grid>grid interface , the select the surface at A (which touching B) and couple with surface at B (which touching A).
this 2 touching part will have fluid pass thru each other on the touching surface.

hope this help.
u can refer to sliding mesh in the tutorial too.

Thanks for your reply. But there is no Grid>grid interface in the FLUENT 6.3.26..
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Old   November 24, 2009, 02:35
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However, what I did is in the gambit I selected surfaces A and B and chose as Interface. Is that OK?
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Old   November 24, 2009, 03:06
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No. U need to do the both.
After u create the 2 touching surface and set them as interface, u need to tell the Fluent too.

sorry , the it should be Define>Grid Interface

give a name for the interface ( whatever name) then select the A on left list and B on right list.. then click create.
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Old   November 24, 2009, 03:11
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Now I understand. Thanks a lot. Lets see what happened...
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Old   November 24, 2009, 03:40
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I am sorry to disturb you again. I did everything according to your suggestion. Select A in Interface Zone 1 and B in Interface Zone 2 and give a name under the Grid Interface and select Coupled in the Interface type. Then it tells 'creating wall -12-shadow' and it creates some walls. Is it OK? But when I went to the boundary conditions I could not find the name I just specified. Please help
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Old   November 24, 2009, 03:59
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Yes. Its ok.
Just run the simulation and u will understand if its working.
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Old   December 10, 2009, 02:01
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Hi
I got some results but it seems it does not work. Actually I have two interfaces. It looks fluid can not move freely through these. Please have a look the temperature contour.

<a href=http://www.freeimagehosting.net/><img src=http://www.freeimagehosting.net/uploads/df9a6df27e.jpg border=0 alt="Free Image Hosting"></a>
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Old   December 10, 2009, 02:42
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Can I ask you a very simple question? I have three concentric cylinders. Is it possible to merge into one?
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Old   December 10, 2009, 02:58
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cannot understand ur question. Please post ur geometry picture.
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Old   December 10, 2009, 03:25
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Hi
In the geometry the red+black cylinder is the inlet. The black cylinder I created for generating triangular mesh. Now I want to merge all three cylinders into one. In gambit I have three volumes. How can I make it one. I tried to go to split/merge volumes and got the message that volumes are disconnected and can not be merged.

Please help.
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File Type: doc geometry.doc (26.0 KB, 29 views)
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Old   December 10, 2009, 03:31
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I think you can understand this geometry well
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Old   December 10, 2009, 03:33
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U want to merge the volume before mesh or after mesh.
I never success merge volume after mesh. I also no idea how to do it.

If u want do it before mesh, u may use Boolen Operation.
u can see the icon with 2 circle overlaping in the Volume area.
The problem of Boolean is u must make sure ur volume is Real volume.
Anyhow, just take a try and gambit will let u know if its impossible.
Boolean Operation have 3 type, Add, Subtract and Intersec.
Add = make 2 touching/overlap volume into 1 volume. All the intersec volume will gone.
Subtract = cut out the overlap of 1 volume into another volume. example, u put a sphere on top on a cube, after u subtract, the shpere will gone and left a sphere hole on it. For sure, u can remain the sphere by ticking retain when substract.

Actually i cannot understand why u want to combine volume. Its sounds like u only want a big cylinder.
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