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Potential use of a porous domain?

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Old   December 22, 2015, 18:30
Default Potential use of a porous domain?
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Hi,

So I am working on this model working on different types of inlet diffusers to maximize diffusing within the room.

I successfully got results like the image with the streamlines. What I did was basically draw these extrudes and then do a Boolean-Subtract.

Now, I am working on a semi circle inlet diffuser as shown. However, I would like this to be porous. I would like to see how well the air is diffused if I have a semi circle enclosure with say 50% volume porosity.

Do I need to specify a new domain? Do I still do a Boolean subtract? I would rather not be specifying new domains as this is a rather large model and i ran into several issues with the interfacing (ended up not using ANSYS's default interfacer for the diffusers that have worked). Little lost here, help?
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File Type: jpg Semicircle.JPG (25.5 KB, 19 views)
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Old   December 22, 2015, 20:03
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Porous regions can be sub domains. They do not need to be an entirely separate domain. But you will still need to define it as a region in your mesh so you can assign it as a porous domain.
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Old   December 22, 2015, 20:12
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So extrude it, and dont do Boolean?

What do you mean by "define it as a region in your mesh." I just have a pretty standard mesh (with a bunch of Edge Sizing).
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Old   December 23, 2015, 06:00
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You will need to make it a multibody part with the rest of the domain, and you will probably have to use a boolean subtract. Then when you define the domain put both regions (both the main region and the subdomain) in the domain definition, and make a subdomain with just the porous region in it.
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Old   December 23, 2015, 10:01
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Alright, I extruded it just like the photo. Now, I did a Boolean Subtract. Now I cannot select this body when I look for faces in the subdomain selection (Since after a Boolean Subtract that body does not exist anymore?)
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Old   December 29, 2015, 15:57
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Alright really need some help here.

How can I do Boolean Subtract AND define that as a subdomain (after a boolean it becomes part of the regular fluid body around it/the cuboid around it)?

Is there any way to define the porosity just within the geometry? So the Boolean subtract is just implemented on like 65% of the shape?
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Old   January 2, 2016, 01:13
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Your questions about the boolean subtract are best asked in the geometry and meshing forum.

But to define a subdomain you will need to somehow define a mesh region. You cannot define mesh regions in CFX-Pre.
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Old   January 7, 2016, 15:58
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Is there a way to possibly not use a subdomain or another domain but just use porous material? Like in the geometry?
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Old   January 7, 2016, 19:24
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I do not understand what you mean. You have to define a region for the solver to apply various physical models. The normal way of doing this is by defining mesh regions.
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Old   January 7, 2016, 20:55
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Could you please explain how to apply "various physical models"? All I ever learned how to mesh was the entire body at a time. How do I tell ANSYS, "Mesh these faces this way, and the other faces some other way."

Also, how will meshing differently help me model a perf metal/porous material?
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Old   January 10, 2016, 02:08
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It sounds like you need to do some meshing tutorials. Have a look at the ANSYS community website, or contact ANSYS support.
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Old   January 10, 2016, 14:26
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I think what Im gonna do is do "cut material" extrudes and make thousands of pores in the material in the geometry. It seems it will end up being a computationally heavy problem, but no reason why it wont work.

It seems porous domains are really making my interfaces go haywire and I need to input variable properties that I have never heard of before.
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Old   January 11, 2016, 12:40
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Haha it is taking 18 hours to converge, and just opening the results file is taking like an hour.

And I havent even done the pattern on all sides yet...too impractical?
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