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-   -   Periodic boundary conditions for 2D pipe (water flow). (http://www.cfd-online.com/Forums/fluent/102686-periodic-boundary-conditions-2d-pipe-water-flow.html)

thess May 31, 2012 11:04

Periodic boundary conditions for 2D pipe (water flow).
 
1 Attachment(s)
Hello,
I'm an MSc student looking for an advice about periodic boundary conditions.

I've modelled 1 metre long pipe, 40mm diameter (see attached).

Boundary conditions defined in ICEMcfd were:
inlet - velocity inlet,
topwall - wall,
bottomwall - wall,
outlet - pressure outlet.
After loading model into fluent I've applied all necessary parameters like materials, BC's, methods and solver. Then I've performed test calculation to see if solution is converging - well it converged (after ~2000 iterations).
Next step is to change bc's into periodic. The goal is to get fully developed flow.

I've followed the instructions from fluent manual:
Quote:

> grid/modify-zones/make-periodic
Periodic zone [()] inlet
Shadow zone [()] outlet
Rotational periodic? (if no, translational) [yes] no
Create periodic zones? [yes] yes
Auto detect translation vector? [yes] yes
...
created periodic zones.
Then I've initialized solution again (using values computed earlier from inlet), and started calculations...

Well after 30000 iterations i still have no solution, and it does not seem to converge. I've tried different mesh densities but the problem still exist.

I'm not sure about my periodic boundaries implementation? Can anyone suggest me where the mistake is?

I'd appreciate anyhelp.

Regards.

A7A May 31, 2012 12:45

Hi,

Have you tried to increase the number of subiterations that been done on the pressure correction.

thess May 31, 2012 13:54

Hello,

Thanks for the reply.

I changed it, simulation is running. But so far I haven't noticed any difference. Well, I'll give it some time.
But I'm afraid it wont solve my problem :(

A7A May 31, 2012 14:38

If it doesnt work, try to make your mesh using ANSYS standard mesher.


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