CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   CFX (http://www.cfd-online.com/Forums/cfx/)
-   -   Periodic BC on Inlet and Outlet of a Duct (http://www.cfd-online.com/Forums/cfx/21467-periodic-bc-inlet-outlet-duct.html)

 Steve July 20, 2005 14:37

Periodic BC on Inlet and Outlet of a Duct

Hi

I was wondering if anyone has experience with applying periodic boundary conditions to the inlet and outlet of a duct, ie making the pipe infinitely long to obtain fully developed flow. I am using TASCflow v.2.12 and it does not like to apply the periodic condition as well as the inlet or outlet condition. Is there a method to get around this problem, possibly to apply a pressure gradient over the duct or define the mass flow rate not directly on the inlet or outlet?

Steve

 stex July 21, 2005 08:27

Re: Periodic BC on Inlet and Outlet of a Duct

Create a subdomain ---> momentum source

Momentum source is like a (DeltaP/L).

Good luck. Ask me if you are in trouble. Bye

 A.W. August 8, 2005 12:03

Periodic BC on Inlet and Outlet of a Duct

Hi, I have a problem in implementation of periodic boundary condition in a duct for a turbulent flow. The way I apply it is: copying outlet velocity multiplying by a factor (for correcting mass) to the inlet and copying pressure at 65% of length of the domain -(Pave at this cross section=65% of domain) to the outlet. I don't know if it is correct.

I know there is another popular method : using the (dp/L=-4*Tauw/Dh) as a momentum source in streamwise direction and copying velocity and pressure to the inlet or outlet. But I can't understand this method.

I really appreciate if someone can help me.