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Old   October 29, 2015, 19:10
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Xuekun Lu
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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 !

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Old   October 30, 2015, 15:04
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Sarang
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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.
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Old   October 30, 2015, 16:25
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Quote:
Originally Posted by Sarang V View Post
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?
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Old   November 2, 2015, 10:49
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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).
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Old   November 2, 2015, 17:24
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Quote:
Originally Posted by Xuekun View Post
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).
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