# Periodic flow pressure drop

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 December 7, 2017, 13:45 Periodic flow pressure drop #1 New Member   Devshi Ziyad Join Date: Oct 2015 Posts: 10 Rep Power: 9 Hello, I have simulated periodic flow across a channel. with wall on one side and periodic flows on two sides. Since it is periodic flow, pressure drop is zero. And the only condition given is velocity initial condition in x direction. Can you tell me, how I can find pressure drop across the domain in this case. Thanks.

December 7, 2017, 14:08
#2
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Filippo Maria Denaro
Join Date: Jul 2010
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Quote:
 Originally Posted by devshi Hello, I have simulated periodic flow across a channel. with wall on one side and periodic flows on two sides. Since it is periodic flow, pressure drop is zero. And the only condition given is velocity initial condition in x direction. Can you tell me, how I can find pressure drop across the domain in this case. Thanks.
Similar questions in the forum had answers useful for you. The constant pressure drop is a forcing term you have to fix in the streamwise component of the momentum equation

 December 7, 2017, 14:12 #3 New Member   Devshi Ziyad Join Date: Oct 2015 Posts: 10 Rep Power: 9 Thank for your reply. Actually I dont have problem in simulating the flow. In post processing I want to find wall-shear stress. For that I require pressure loss.

December 7, 2017, 14:41
#4
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Filippo Maria Denaro
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Quote:
 Originally Posted by devshi Thank for your reply. Actually I dont have problem in simulating the flow. In post processing I want to find wall-shear stress. For that I require pressure loss.

wall stress (tau_wall) is computed by the velocity gradient at the wall

December 8, 2017, 10:01
#5
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Quote:
 Originally Posted by FMDenaro wall stress (tau_wall) is computed by the velocity gradient at the wall
Yes, I completely agree with that. thanks.

I was wondering if pressure gradient is not specified beforehand, and just volume flow rate is specified, how do I get the pressure gradient across the domain.

 Tags channel flow, periodic bc, pressure drop