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 fisicas1 November 15, 2012 14:12

inicial condition!

hi guys!

I have a geometry with a outlet and two inlets, I would like to impose a different pressure for each inlet, I am using as intel (velocity inlet) therefore I have the same pressure for both. someone could tell me the way to have diferente pressures for my inlets.

 abdul099 November 15, 2012 20:03

First: That has nothing to do with initial conditions.

You will not have the same pressure for both inlets, even when you're using a velocity inlet. EXCEPT your physics will result in the same pressure drop in both flow paths of your geometry. This is because the pressure drop depends on your geometry and flow velocities. So let's assume, you have a Y pipe. You'll have different pressure drops in both legs of the Y when you have different velocities. Since the outlet pressure is the same (no matter what pressure level it is), this results in different inlet pressures.

 fisicas1 November 16, 2012 08:50

my first way.

with the initial condition of my pressure I can impose this pressure in my inlets (both) with solvers->Segregated flow-> Pressure, but I need to have 2 different pressure.

if I use Stagnation Inlet, I want to impose the pressure in my inlets, but when I used this boundary my velocity is very high, the simulation is divergente. maybe I am confused with:

supersonic Static Pressure (??)

total pressure (4MPA)

total temperature (360C)

Thanks so much

 LuckyTran November 16, 2012 20:50

Quote:
 Originally Posted by fisicas1 (Post 392515) my first way. with the initial condition of my pressure I can impose this pressure in my inlets (both) with solvers->Segregated flow-> Pressure, but I need to have 2 different pressure.
That is the correct way to impose a pressure inlet boundary condition (if that is indeed what you are trying to do).

Quote:
 Originally Posted by fisicas1 (Post 392515) supersonic Static Pressure (??) total pressure (4MPA) total temperature (360C)
supersonic Static Pressure is the absolute static pressure
total pressure is the stagnation pressure
total pressure is the stagnation temperature

You should use the isentropic relations to relate the static pressure to total pressure and total temperature (Mach number pops in here).

the stagnation inlet can give rise to supersonic flow at the inlet so be careful.

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