Periodic B.C.

Volvic · January 25, 2013, 12:01

Hi guys,

Has anyone attempted to impose a Periodic B.C. in stream-wise and span-wise of a duct geometry?

Thank you in advance!

flotus1 · January 28, 2013, 03:36

Yes, I have tried this before.

If you have any specific questions, feel free to ask.

sfotovati · September 9, 2013, 17:09

I have cube and I want to have periodic flow in the lets say X direction. the Y and Z directions are bounded by walls. The mass flow rate for this periodic condition is known.

I am using Ansys 14.5 for meshing, but I do not know how to define the periodic BC in it. Can anyone tell me how to make the periodic BC with defined mass flow rate in either Fluent or ansys meshing?

Thanks,

Shawn

Far · September 9, 2013, 17:33

Just define periodic boundary conditions either in mesher or solver. And put mass flow rate, flow direction and bulk temperature. Pressure gradient will be calculated automatically by fluent for the specified flow rate.

sfotovati · September 9, 2013, 19:00

I just figured it out. This is how I did it:

I made sure that the pair faces have identical mesh. I named them differently, and then in the Fluent, using TUI for "mesh/modify-zones/make-periodic", I changed the boundary to the periodic, and then set the pressure gradient or mass flow rate for the boundary in the "Boundary Condition" in the "Periodic Condition" section.

However, if I want to have additional pair of periodic BC, for example, in both X and Z directions, then the mesh failed and took negative values. I have no idea why this happened! Has anyone noticed it?

quantities · September 11, 2013, 22:07

If you wanna set more than one pair of periodic boundary, I suggest you set the boundary as interface in mesh generator first and then make the periodics in the interface panel of FLUENT.

Shahr · September 24, 2013, 10:30

Quote:

Originally Posted by Far

Just define periodic boundary conditions either in mesher or solver. And put mass flow rate, flow direction and bulk temperature. Pressure gradient will be calculated automatically by fluent for the specified flow rate.

I am trying to simulate a very simple channel flow with periodic boundary condition at the inlet and outlet. I have already did what you mentioned. But my solution doesn't converge, or when it converges, the pressure field does not show a linear pressure drop. The are pressure maxima and minima spots somewhere in the middle of my channel. Any suggestion?

January 25, 2013, 12:01	Periodic B.C.	#1
Volvic New Member John Join Date: Mar 2012 Posts: 7 Rep Power: 14	Hi guys, Has anyone attempted to impose a Periodic B.C. in stream-wise and span-wise of a duct geometry? Thank you in advance!

January 28, 2013, 03:36		#2
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,399 Rep Power: 46	Yes, I have tried this before. If you have any specific questions, feel free to ask. Last edited by flotus1; January 28, 2013 at 04:55.

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September 9, 2013, 17:09		#3
sfotovati Member Shawn Fotovati Join Date: Jul 2009 Location: Dallas, TX Posts: 42 Rep Power: 16	I have cube and I want to have periodic flow in the lets say X direction. the Y and Z directions are bounded by walls. The mass flow rate for this periodic condition is known. I am using Ansys 14.5 for meshing, but I do not know how to define the periodic BC in it. Can anyone tell me how to make the periodic BC with defined mass flow rate in either Fluent or ansys meshing? Thanks, Shawn

September 9, 2013, 17:33		#4
Far Super Moderator Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,553 Blog Entries: 6 Rep Power: 54	Just define periodic boundary conditions either in mesher or solver. And put mass flow rate, flow direction and bulk temperature. Pressure gradient will be calculated automatically by fluent for the specified flow rate.

September 9, 2013, 19:00		#5
sfotovati Member Shawn Fotovati Join Date: Jul 2009 Location: Dallas, TX Posts: 42 Rep Power: 16	I just figured it out. This is how I did it: I made sure that the pair faces have identical mesh. I named them differently, and then in the Fluent, using TUI for "mesh/modify-zones/make-periodic", I changed the boundary to the periodic, and then set the pressure gradient or mass flow rate for the boundary in the "Boundary Condition" in the "Periodic Condition" section. However, if I want to have additional pair of periodic BC, for example, in both X and Z directions, then the mesh failed and took negative values. I have no idea why this happened! Has anyone noticed it?

September 11, 2013, 22:07		#6
quantities New Member Join Date: Sep 2013 Location: Shanghai China Posts: 6 Rep Power: 12	If you wanna set more than one pair of periodic boundary, I suggest you set the boundary as interface in mesh generator first and then make the periodics in the interface panel of FLUENT.