Learning Forum

[narendrapatel111]

I have two infinitely long and wide flow zones- (1) free flow zone and (2) porous flow zone and both zones make an interface so that water can flow from one zone to other zone. Can I assign two periodic boundary conditions: First for Inlet 1 and Outlet 1; second for Inlet 2 and Outlet 2 as shown in figure? Is interface an issue? I have same pressure drop between inlets and outlets for both zones.

 

[narendrapatel111]

[Amine Ben Hadj Ali]

If pressure drop related periodicity you will have a single streamwise direction. Also check if you are hitting any limitations.

[Karthik Remella]

Hello,

I've got a feeling that this might not be allowed. I'll have to test this out and get back to you. 

Thanks.

Karthik

[narendrapatel111]

I have pressure drop only in streamwise direction. My concern is I have two inlets and two outlets, hence I have to assign two periodic BCs. Both flow zones make an interface.  In spanwise/lateral direction, I have no pressure drop and I can assign wall BC (or symmetry to make domain wider) for sides.

Karthik, please check it. Userguide says no source or sink is allowed between the periodic BC, this is the limitation I found but didn't find details if two periodic BCs  with interface can be applied.

Thanks.

[narendrapatel111]

Hi Karthik, Did you test it? Thanks. Narendra

[Karthik Remella]

Hello,

My apologies for the delay. Yes, you should be able to do this in Fluent. Please use the following TUI commands to make the periodic boundary conditions.

Here are some screenshots.

TUI command:

/mesh/modify-zones> make-per

Output on Fluent Console:

Periodic zone [()] per-a-bot

Shadow zone [()] per-b-bot

Rotationally periodic? (if no, translationally) [yes] no

Create periodic zones? [yes] 

Auto detect translation vector? [yes] 

  computed translation deltas: 0.020000 -0.000000 0.000000 

  zone 9 deleted

Please let me know if this works for you.

Thanks.

Karthik

 

 

[narendrapatel111]

Hi, I tried this. I encountered a doubt about flow direction. I assigned flow direction, lets say +X direction (1,0,0) and assigned pressure gradient (+ve value) then I see flow moving in -ve X direction. Does it decide direction based on direction assigned to velocity components in initialization or naming of the faces? I want to make sure that I am not messing up with directions assigned to values I enter in GUI. Thanks.

[narendrapatel111]

HI Karthik, Could you please check it and tell me. Also, I am getting lower velocity than expected value. Any suggestion would be appreciated.

Thanks.

[Karthik Remella]

Hello,

The flow is based on the pressure gradient you assign. This is what dictates whether you have a +ve or -ve value of velocity along the X direction. 

Does this answer your question? If it does, please feel free to make the most appropriate answer as 'Is Solution' to benefit the community.

Thanks.

Karthik