Periodic Boundary conditions

dale154 · August 31, 2015, 06:26

Hello, i am modeling a 2D cascade using Ansys Fluent. I am trying to employ periodic boundary conditions to the upper and lower surfaces of the flow boundary. However when i do this (B.C = interface then mesh interfaces-periodic) Fluent creates new 'boundaries' and makes them walls, these new 'boundaries' seem to be where the boundaries that were made periodic where. Does anyone know why Fluent does this and should it do this.
Carrying on with these settings (using a k-omega) model the residuals seem to oscillate and do not converge, i wonder if this is the problem.
Your help is very much appreciated!
Dale.

Far · August 31, 2015, 09:43

First of all it is normal and it is internal working of Fluent.

Convergence problem has nothing to do with the periodic problem. Check your mesh etc...

However I would strongly recommend that you should try you best to get 1:1 periodicity in your model.

dale154 · August 31, 2015, 10:15

Hi, thanks for clearing this up for me.
What exactly is meant by 1:1 Periodicity?

August 31, 2015, 06:26	Periodic Boundary conditions	#1
dale154 New Member Join Date: Aug 2015 Posts: 22 Rep Power: 9	Hello, i am modeling a 2D cascade using Ansys Fluent. I am trying to employ periodic boundary conditions to the upper and lower surfaces of the flow boundary. However when i do this (B.C = interface then mesh interfaces-periodic) Fluent creates new 'boundaries' and makes them walls, these new 'boundaries' seem to be where the boundaries that were made periodic where. Does anyone know why Fluent does this and should it do this. Carrying on with these settings (using a k-omega) model the residuals seem to oscillate and do not converge, i wonder if this is the problem. Your help is very much appreciated! Dale.

August 31, 2015, 09:43		#2
Far Super Moderator Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,552 Blog Entries: 6 Rep Power: 53	First of all it is normal and it is internal working of Fluent. Convergence problem has nothing to do with the periodic problem. Check your mesh etc... However I would strongly recommend that you should try you best to get 1:1 periodicity in your model. dale154 likes this.

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August 31, 2015, 10:15		#3
dale154 New Member Join Date: Aug 2015 Posts: 22 Rep Power: 9	Hi, thanks for clearing this up for me. What exactly is meant by 1:1 Periodicity?