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How to make periodic walls in FLUENT?

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Old   October 5, 2015, 05:30
Default How to make periodic walls in FLUENT?
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Hello how i can make the top and bottom walls of the 3D channel shown in pictures as periodic?

help me pls
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File Type: jpg 1.jpg (193.7 KB, 270 views)
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Old   October 5, 2015, 05:39
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Hi, if your solving in Fluent you can firstly set the walls as 'interface' boundary conditions. Then under 'mesh interfaces' you can make them periodic.

Dale.
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Old   October 5, 2015, 05:47
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Hi Dale thanks for the reply. Yes I used FLUENT for solving I set now the walls as interface boundary in fluent as use said but cannot find option called "mesh interfaces"? may you send me illustrated picture ??

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Hi, if your solving in Fluent you can firstly set the walls as 'interface' boundary conditions. Then under 'mesh interfaces' you can make them periodic.

Dale.
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Old   October 5, 2015, 05:50
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No problem. The second image is the pop-up window that should appear when you click 'create/edit', this allows you to then set the periodic conditions.

you can also set periodic boundary conditions using text input, but i find this method easier.
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Old   October 5, 2015, 06:32
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I want tell you what I did please check for me if something wrong:
1) I was called the top wall as int1 and bottom wall as int2 and set boundary condition for both as interface in boundary conditions.
2) I chose mesh interfaces then press create>give name as per then select interface zone 1 as int1 (top wall) and interface zone 2 as int2 (bottom wall)? is that selecting correct?
3) what interface option should i select? as i see there are four options:
a) periodic boundary condition?
b) periodic repeats?
c)coupled wall?
d) Matching?

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No problem. The second image is the pop-up window that should appear when you click 'create/edit', this allows you to then set the periodic conditions.

you can also set periodic boundary conditions using text input, but i find this method easier.
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Old   October 5, 2015, 07:32
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Yes, so far seems correct. The interface option depends on what you want. If you want periodic boundary conditions (as said at the beginning of the post), select that (The ANSYS manual has good descriptions and diagrams of each of these if you're unsure). Once selected you need to select if the periodicity is rotational or translation,from your description it seems to be translation. You then need to tell it the offset, you can select 'auto compute offset' but if this doesn't work, simply enter the co-ordinates.
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Old   October 5, 2015, 07:44
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OK if i select periodic boundary conditions in periodic conditions window it tell me two options mass flow rate or pressure gradient ? i do not want to select mass flow rate because no fluid pass through these walls hence I select pressure gradient is it correct in this case? i leave default values for pressure and bulk temperature but change flow direction to (0,0,1) instead of (1,0,0) because z is the axial direction??

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Yes, so far seems correct. The interface option depends on what you want. If you want periodic boundary conditions (as said at the beginning of the post), select that (The ANSYS manual has good descriptions and diagrams of each of these if you're unsure). Once selected you need to select if the periodicity is rotational or translation,from your description it seems to be translation. You then need to tell it the offset, you can select 'auto compute offset' but if this doesn't work, simply enter the co-ordinates.
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Old   October 5, 2015, 07:52
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Originally Posted by mariam.sara View Post
OK if i select periodic boundary conditions in periodic conditions window it tell me two options mass flow rate or pressure gradient ? i do not want to select mass flow rate because no fluid pass through these walls hence I select pressure gradient is it correct in this case? i leave default values for pressure and bulk temperature but change flow direction to (0,0,1) instead of (1,0,0) because z is the axial direction??
Can you send a picture of the periodic conditions window?
Also i think you maybe don't want periodic boundary conditions if you don't want fluid to pass through.
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Old   October 5, 2015, 09:43
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To create a periodic boundary you can also enter into the TUI:
/define/boundary-conditions/modify-zones/make-periodic
and then answer the prompts
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Old   October 5, 2015, 15:58
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Dale actually I attempt to validate a paper it set a periodic wall as boundary I never sure if there is motion at the periodic boundary or no so may you assist me with understanding it? the boundary conditions illustrated in Fig. 2 at the paper you can find the paper attached at the site:

https://drive.google.com/file/d/0Byd...ew?usp=sharing


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Can you send a picture of the periodic conditions window?
Also i think you maybe don't want periodic boundary conditions if you don't want fluid to pass through.
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Old   October 6, 2015, 06:53
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From the ANSYS Manual: "Periodic boundary conditions are used when the physical geometry of interest and the expected pattern of the flow/thermal solution have a periodically repeating nature"



i.e if your structure repeats or if you want take advantage of symmetry you can use periodic conditions (see attached images, also from the ANSYS manual, i also attach a image from some of my own results to help illustrate this). You can also see the effect of the periodic boundary conditions in Figure 11 of the document referenced in the way that the outer edges are effected by the outer edge of the opposite channel

From what i gather from your model, there is no fluid flow between the upper and lower walls, but there is a heat flow. I believe you want to simulate the heat flow through the channel and not fluid flow (I'm afraid i don't have much experience with heat flows only fluid flows).


Dale.
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Old   October 6, 2015, 16:12
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I think coupled option is the appropriate option for my case

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Originally Posted by dale154 View Post
From the ANSYS Manual: "Periodic boundary conditions are used when the physical geometry of interest and the expected pattern of the flow/thermal solution have a periodically repeating nature"



i.e if your structure repeats or if you want take advantage of symmetry you can use periodic conditions (see attached images, also from the ANSYS manual, i also attach a image from some of my own results to help illustrate this). You can also see the effect of the periodic boundary conditions in Figure 11 of the document referenced in the way that the outer edges are effected by the outer edge of the opposite channel

From what i gather from your model, there is no fluid flow between the upper and lower walls, but there is a heat flow. I believe you want to simulate the heat flow through the channel and not fluid flow (I'm afraid i don't have much experience with heat flows only fluid flows).


Dale.
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Old   September 14, 2017, 09:50
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Quote:
Originally Posted by mariam.sara View Post
I think coupled option is the appropriate option for my case
Hi.
I have the same problem and I can't find the way. Can you please help me about the boundary conditions?
I simulated it with wall boundary condition and it seems true. But I can't put periodic boundary conditions on top and bottoms of the geometry. Please help.

Thanks
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