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How to set a thin surface using CFX4.4?

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Old   January 14, 2004, 22:30
Default How to set a thin surface using CFX4.4?
  #1
paul
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Hi, everyone.

I created a small solid in a large solid and named the small solid's surfaces as wall1. But it seemed invalid. Air flows through it just as there isn't any thin surface. I don't know why. someone told me that I should set an interblock boundary between the two blocks.And I set one, then I received an error message: " ERROR: UNUSED INTERBLOCK BOUNDARY PATCH WITH NAME 'BLKBDY1 ' THIS NAME DOES NOT APPEAR UNDER ANY GLUE PATCHES COMMAND". I don't know why. Can anyone help me?

Thanks.

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Old   January 16, 2004, 19:46
Default Re: How to set a thin surface using CFX4.4?
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Jeff
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Paul,

It doesn't sound as though your solids are connected. CFX-4 is a multiblock code and all blocks/solids have to meet at full faces.

Create the large block. Break it on two planes in each of the three coordinate directions such that the breaks describe the dimensions of the internal blockage. This will create 27 blocks with the center one being your blockage. If you want it to conduct heat, turn that block into a conducting solid. If not, simply delete it from the domain and name the 6 internal surfaces that are left as walls.

Hope this helps.
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Old   January 17, 2004, 01:30
Default Re: How to set a thin surface using CFX4.4?
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paul
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Hi, Jeff. Thank you for your answer.It works. Thanks.
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Old   January 17, 2004, 03:09
Default Re: How to set a thin surface using CFX4.4?
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paul
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But it's very inconvenient if I want to set many thin surface in a solid. The solid need to be break into lots of small solid. Do you have some convenient ways? Thanks.
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Old   January 17, 2004, 12:12
Default Re: How to set a thin surface using CFX4.4?
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Jan Rusås
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I don't understand your problem thin surfaces, are thin surface rally what you need or is it just walls? The small cube in a large can also be created in a simpler manner.

Create the 6 surcases on each of the large and small cube, connect the surfaces from the small to the large to create a solid - total 6 solids. The you have your obstruction as the small one. It does not results in a nice grid as splitting it into more solids.

If you prefer the solution with the many solids, remember you can to it a bit easy way by extruding surfaces and translate solids etc. not so difficult.
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Old   January 17, 2004, 21:14
Default Re: How to set a thin surface using CFX4.4?
  #6
paul
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Hi, Jan. Thank you for your answer. Now I'm simulating the velocity and temperature field of the power station boiler.You know, there are many small panels at the top of the furnace. In a simple way, the small panel can be regard as wall(thin surface).So the top of furnace(the large solid) must split into many solids to get the panel's figure.And I think it's very inconvenient.
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Old   January 18, 2004, 01:23
Default Re: How to set a thin surface using CFX4.4?
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Jan Rusås
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What confuses me is that you say thin surface, you dont need a solid for a thin surface. I you have som places where you want a wall( thin surface) the work around could be to create the mesh such that you have cells where you want the surfaces and then declare them in your command file. I am not sure if it works for you, but I have used this approach for guiding plates in ducts (when I used 4.4)
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Old   January 18, 2004, 20:42
Default Re: How to set a thin surface using CFX4.4?
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Jeff
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Jan Rusas' advice is correct. The only tricky part is that you have to know what your block orientation is and some planning needs to go into the number of grid cells so that the grid boundaries line up with where you want your baffles. Then you can use >>CREATE PATCH to create a THIN SURFACE type patch on a cell region. With lots of baffles, this is probably worth the effort, especially if you're experimenting with number and placement of baffles.

As I said, figuring out the block orientation so that you know what I,J,K extents to create the patch is the trick. Try using CFX-Analyse to create regions at various locations and showing the region to make sure you've got it in the right place. Just remember that for an LxNxM cell grid, Analyse plots on (L+1)x(N+1)x(M+1) vertices.

Jeff
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Old   January 18, 2004, 22:49
Default Re: How to set a thin surface using CFX4.4?
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Jan Rusås
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If I remember the old build correct then it is possible to control the I,J,K direction, that makes it a bit easier to create the patches. Good old build ))
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Old   January 19, 2004, 22:53
Default Re: How to set a thin surface using CFX4.4?
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Jeff
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I think you're remembering good old MeshBuild. It used to let you create blocks and set the orientations. Build (Patran) does not.

Jeff
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