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-   -   "Periodic" boundary (https://www.cfd-online.com/Forums/cfx/20487-periodic-boundary.html)

 Stex July 12, 2004 07:18

"Periodic" boundary

Hi, I'm studying the flow inside a single pipe heat exchanger. I use CFX with the "Periodic" boundary. After trying some value of "momentum source" I find the right one to carry out the mass flow I need. But after all I found a value of the pressure equal both on the inlet and outlet. So how can I calculate the Pressure Drop? Thank you very much.

 Derrek July 12, 2004 11:00

Re: "Periodic" boundary

Define an expression such as "deltaP" = massFlowAve(ptot)@thenameofyourinlet -massFlowAve(ptot)@thenameofyouroutlet.

Then in the Output Control. Define a monitor point and define it as an expression = deltaP..

When you go to Post, you will have an expression defined that automatically calculates your pressure drop..

Derrek

 Stevie Wonder July 13, 2004 09:26

Re: "Periodic" boundary

If you have a periodic BC, your local pressure drop in the streamwise direction is:
dp = p(PERIODIC PLANE1)-p(PERIODIC PLANE2)

If your periodic domain has 1m length, the pressure drop of 50m will be 50 * dp.

If you want to model pressure drop I think you should consider a domain with an inlet/outlet instead.
Good luck, Stevie Wonder

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