# concept of periodic conditions

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 January 22, 2014, 06:44 concept of periodic conditions #1 Member   Join Date: Dec 2013 Posts: 53 Rep Power: 5 How can we use same periodic conditions to 1.flow with a pressure drop,which is geometrically periodic in nature,and is not fully developed. and also to 2.Flow with a pressure drop,and fully developed flow(like fully developed flow through circular pipe) Iam getting confused.

January 22, 2014, 07:21
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Filippo Maria Denaro
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Quote:
 Originally Posted by myaccount How can we use same periodic conditions to 1.flow with a pressure drop,which is geometrically periodic in nature,and is not fully developed. and also to 2.Flow with a pressure drop,and fully developed flow(like fully developed flow through circular pipe) Iam getting confused.

case 2 is for example the flow driven by a pressure gradient in a channel. You can decompose your pressure in two terms, one is the mean constant pressure gradient you use as forcing in the momentum equation, the second is the "fluctuation" that you set periodic. This last term is governed by the Poisson equation for incompressible flows

 January 22, 2014, 09:35 concept of periodic conditions #3 Member   Join Date: Dec 2013 Posts: 53 Rep Power: 5 Thanks for the response. Can you please explain me how can be the same periodic conditions procedure be applied such that we find du/dx=0 in second case and du/dx not equal to zero in first case.

 March 25, 2014, 00:57 pressure drop in periodic flow #4 Member   Join Date: Dec 2013 Posts: 53 Rep Power: 5 Hi I have simulated flow over solids through a channel.I have applied periodic boundary conditions at the inlet and exit of the pipe. Can I use the pressure drop indicated in periodic boundary conditions menu after the convergence of the case as pressure drop /L for my further work? Any one please clarify.

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