Baffle/Internal Wall (Surface as wall)

saml · November 11, 2015, 01:33

Hi,

I am trying to create baffles inside a fluid domain similar to this video on YouTube (https://www.youtube.com/watch?v=U1Mzw8aDlL0). Could anyone give me pointers on how to create baffles within a fluid domain?

I have tried creating a simple cylindrical (fluid) tube with a surface inside the fluid. I believe I have meshed both the fluid and and surface using workbench. I have then named the fluid with inlet, outlet, wall, fluid and the surface "baffle." The surface was selected using the body select function.

Problem is that when I open Fluent, under the boundary condition, the named selection "baffle" is not there to be selected. The other boundary conditions are there. Essentially, the baffle surface is not recognised in Fluent. Any ideas/help would be greatly appreciated!

Thanks,
Sam

saml · December 18, 2015, 06:39

Still trying to figure this out, any tips?

divergence · December 18, 2015, 06:54

You mentioned that you used the body select tool in naming the baffle surface. Have you tried naming the surface by using the surface tool? It might be possible that you have the volume named baffle instead of the surface.

If that doesn't work, you could always try to separate the volumes with a small suppressed/cut volume (a couple of millimeters thich or something else suitable for your case) instead of a plain surface baffle.

saml · December 18, 2015, 07:17

Thanks for the suggestion! I've tried both and appeared that it didn't make a difference. Attached is screen shot of what's happening. With my problem I wanted to avoid making a small volume but I will do so if I find Fluent doesn't allow 0 thickness surfaces acting as internal wall, which I think it can looking around. Just need to figure out how to implement it.

divergence · December 18, 2015, 07:45

Yeah, I get that you wouldn't want to have too small volumes.

Regarding the "named selection.jpg" picture, you could try to divide the volume with the baffle and then try to imprint the baffle surface on both of the volumes. Or one of them, can't say which would be better.

CeesH · December 18, 2015, 08:02

Hi,

What I always do for my stirred tanks:

- I cut the cylinder in (4) sections by xy/ yz slice in the geometry editor.
- and I make a cyllindrical slice with a diameter of, say, 0.8T (if the baffle extend is 0.1T on each side)
- I make named selections of the resulting interfaces in the geometry editor or the mesher.
- In FLUENT, these interfaces pop up in the boundary condition menu as interior, but you can change them to wall. This will add a 'baffle.shadow', but that's fine. Set baffle.shadow and baffle as no slip walls, and all should be fixed.

November 11, 2015, 01:33	Baffle/Internal Wall (Surface as wall)	#1
saml New Member Join Date: Jun 2015 Posts: 6 Rep Power: 10	Hi, I am trying to create baffles inside a fluid domain similar to this video on YouTube (https://www.youtube.com/watch?v=U1Mzw8aDlL0). Could anyone give me pointers on how to create baffles within a fluid domain? I have tried creating a simple cylindrical (fluid) tube with a surface inside the fluid. I believe I have meshed both the fluid and and surface using workbench. I have then named the fluid with inlet, outlet, wall, fluid and the surface "baffle." The surface was selected using the body select function. Problem is that when I open Fluent, under the boundary condition, the named selection "baffle" is not there to be selected. The other boundary conditions are there. Essentially, the baffle surface is not recognised in Fluent. Any ideas/help would be greatly appreciated! Thanks, Sam triimaran likes this.

December 18, 2015, 07:45		#5
divergence Member Join Date: Mar 2014 Posts: 56 Rep Power: 12	Yeah, I get that you wouldn't want to have too small volumes. Regarding the "named selection.jpg" picture, you could try to divide the volume with the baffle and then try to imprint the baffle surface on both of the volumes. Or one of them, can't say which would be better. triimaran likes this.

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December 18, 2015, 06:39		#2
saml New Member Join Date: Jun 2015 Posts: 6 Rep Power: 10	Still trying to figure this out, any tips?

December 18, 2015, 06:54		#3
divergence Member Join Date: Mar 2014 Posts: 56 Rep Power: 12	You mentioned that you used the body select tool in naming the baffle surface. Have you tried naming the surface by using the surface tool? It might be possible that you have the volume named baffle instead of the surface. If that doesn't work, you could always try to separate the volumes with a small suppressed/cut volume (a couple of millimeters thich or something else suitable for your case) instead of a plain surface baffle.

December 18, 2015, 08:02		#6
CeesH Senior Member Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0	Hi, What I always do for my stirred tanks: - I cut the cylinder in (4) sections by xy/ yz slice in the geometry editor. - and I make a cyllindrical slice with a diameter of, say, 0.8T (if the baffle extend is 0.1T on each side) - I make named selections of the resulting interfaces in the geometry editor or the mesher. - In FLUENT, these interfaces pop up in the boundary condition menu as interior, but you can change them to wall. This will add a 'baffle.shadow', but that's fine. Set baffle.shadow and baffle as no slip walls, and all should be fixed.