# Static Pressure Question

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 October 29, 2015, 19:10 Static Pressure Question #1 New Member   Xuekun Lu Join Date: Oct 2015 Posts: 20 Rep Power: 10 Hello, I am modelling a laminar incompressible flow in the S pipe. The inlet velocity is quite small, generating Re=500, pressure outlet = 1 atm. Initial condition is P=1 atm. Why the static pressure is larger at the inlet than the outlet? Is this because the velocity at inlet is lower than outlet so Bernoulli's equation calculated a larger static pressure? Is my understanding correct? The pressures I defined in the beginning is the static pressure or total pressure? I need your help ! Thanks ! [IMG][/IMG] [IMG][/IMG]

 October 30, 2015, 15:04 #2 New Member   Sarang Join Date: Oct 2015 Posts: 22 Rep Power: 10 If you are specifying velocity at the inlet and a static pressure at the outlet then then I would expect the static pressure to be high to drive the flow through the outlet.

October 30, 2015, 16:25
#3
New Member

Xuekun Lu
Join Date: Oct 2015
Posts: 20
Rep Power: 10
Quote:
 Originally Posted by Sarang V If you are specifying velocity at the inlet and a static pressure at the outlet then then I would expect the static pressure to be high to drive the flow through the outlet.
Hi, thanks a lot for your reply. I just wander how the solver calculate the static pressure higher at inlet than outlet since I define the initial condition is 1 atm, same as outlet. Is this 1 atm the static or total pressure?

 November 2, 2015, 10:49 #4 New Member   Sarang Join Date: Oct 2015 Posts: 22 Rep Power: 10 As you said it is just an initial condition. Your initial conditions gets washed way as your simulation progresses. Initial conditions should not affect your end solution for a continuous flow problem (You might get convergence issues if they are set really bad).

November 2, 2015, 17:24
#5
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Matt
Join Date: Aug 2014
Posts: 947
Rep Power: 17
Quote:
 Originally Posted by Xuekun Hi, thanks a lot for your reply. I just wander how the solver calculate the static pressure higher at inlet than outlet since I define the initial condition is 1 atm, same as outlet. Is this 1 atm the static or total pressure?
you must have a pressure gradient to have velocity (i.e. flow).