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Old   January 14, 2008, 16:47
Default Periodic Boundary
  #1
Mann
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Hi

I am simulating a flow in a square duct with four cubes inside it. I want to set up a periodic boundary condition for my flow. In order to do that i first created a domain interface for inlet and outlet and set a translational peridocity as interface model. I have following questions:

1) Do i have to specify change in pressure? If yes how can i calculate it.

2) I would like to specify constant pressure gradient of -1.59 Pa m^-1. How can i do that!

Thanks for your help!!
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Old   January 15, 2008, 16:51
Default Re: Periodic Boundary
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Glenn Horrocks
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Hi,

1) You need to specify something to get the flow moving!

2) From your other posts it looks like translational periodicity with a pressure difference might be appropriate. If your duct is 1 metre long then my guess is the pressure drop would be 1.59 Pa. I will let you guess what the pressure drop is for other lengths.

Glenn Horrocks
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Old   January 15, 2008, 19:24
Default Re: Periodic Boundary
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Mann
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Can i not specify constant pressure within every cell of my domain to get the flow moving. Thats what they seem to have done in the paper. But my problem is i dont quite know how to do it! If anyone out there can give any input it will be very helpful. I am using LES smagorinsky model!.

Mann
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Old   January 16, 2008, 04:54
Default Re: Periodic Boundary
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Glenn Horrocks
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Hi,

As previously stated setting a constant pressure gradient per cell cannot be done. This is especially so if you are doing a LES simulation! You need the pressure field to couple with the velocity field to get something of physical meaning.

Glenn Horrocks
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