[Angeline]

Hi Guys

My case is gas solid flow in a pipe. Instead of simulating a long pipe , I take a small length using periodic BC. After every iteration the values from outlet will be updated in inlet. I want to write a UDF for this.

Can anybody help me please.


Regards
Angie

[Amir]

Hi Angie,
If you don't want to use FLUENT periodic BC (maybe for its restrictions ?), you have to loop over desired faces with an exhaustive search. (it's much more better to have same topologies in two faces)

Regards,

Amir

[Angeline]

Thanks Amir for your reply.

Can you please elaborate it more for me to understand.......


Regards
Angie

[Amir]

Originally Posted by Angeline

Thanks Amir for your reply.

Can you please elaborate it more for me to understand.......


Regards
Angie

First, ensure whether you can use periodic boundary condition of FLUENT or not; check its restrictions in user manual. If you can use that, it wouldn't need any UDF.
If it doesn't the case, for writing UDF and for simplicity, use the same topology on both faces which you want to project data. After that, you can use 2 procedures:
1) if you have used same topologies and strategies in creating faces, FLUENT searchs faces' elements in the same manner, so you can write data in a temporary files and then use them; in this method, you have to ensure same searching manner.
2) in this method you can use exhausting search between to faces to achive appropriate cells to which you want to project data. (using this method is not reasonable and also time-consuming and it isn't recommended)

Regards,

Amir

[raghu.tejaswi]

Hi Angeline, Amir

I assume the use of periodic BC is to reduce the computational domain. I have been using it to update the values of outlet to inlet in a 2D flow.
I am basically using it to achieve a fully developed flow (Thermally and hydrodynamically).

Amir: Could you pls clarify if I can really use periodic BC to achieve fully developed temperature profile? My results from simulations match with the analytical results but the temperature profile doesnt seem to maintain constant even after 10m length of the pipe. Is there anything I need to note before using periodic BC?

Raghu

[macfly]

Hi Raghu,

Thermally fully developed doesn't mean that temperature profile no longer changes. It is the relative shape of the profile that no longer changes, and the local convection coefficient becomes a constant independent of flow axis.

[Luttappy]

Hi all
I was working on Periodic Boundary condition for a wavy channel considering one module at a time in Fluent at very low Re (Laminar and steady).
In this case except continuity both momentum and energy equations are converging.
What might be the reason for this issue
Thanks in Advance.