Code Saturne Outlet pressure

  • AndreaF
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10 years 4 months ago #5547 by AndreaF
Code Saturne Outlet pressure was created by AndreaF
Hi to all.

I'd like to simulate a suction fan.

in this case I need to impose a pressure at the outlet (I know the diagram of the fan velocity - pressure).

In which way I can set up a pressure BC for the outlet in code saturne?

Thanx to all<br /><br />Post edited by: AndreaF, at: 2011/06/07 19:19

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10 years 4 months ago #5551 by Torben
Replied by Torben on topic Re:Code Saturne Outlet pressure
An outlet boundary condition is a free flow into a pressure corresponding to the reference pressure.

In the GUI (v1.3.3): Physical properties -&gt; Reference values -&gt; Reference pressure.

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10 years 4 months ago #5552 by AndreaF
Replied by AndreaF on topic Re:Code Saturne Outlet pressure
Thanx for your answer.

The Fan create a pressure drop of about 100Pa.

If I set the reference pressure = 101325 Pa (standard pressure ) - 100 Pa = 101225Pa, in which way can I setup the pressure for the inlet?

Many thanx for the help

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10 years 4 months ago #5553 by Torben
Replied by Torben on topic Re:Code Saturne Outlet pressure
Another way, which does not affect physical parameters is to alter the parameter &quot;PRED0&quot;. See user manual p. 137:

PRED0 RA real number [0.D0] O L3
for each phase IPHAS, PRED0(IPHAS) is the reference value for the reduced pressure P&amp;#8727; (see RO0) it is especially used to initialise the reduced pressure and as a reference value for the outlet boundary conditions for an optimised precision in the resolution of P &amp;#8727; , it is wiser to keep PRED0 to 0
with the compressible module, the “pressure” variable appearing in the equations directly represents the total pressure. It is therefore initialised to P0 and not PRED0 (see RO0)
always useful, except with the compressible module


PRED0 can be changed in SUBROUTINE USIPSU in user fortran file usini1.f In the standard usini.f around line 1230 you find:

[code:1] IPHAS = 1
C
T0 (IPHAS) = 1000.D0 + 273.15D0
P0 (IPHAS) = 1.013D5[/code:1]Here you can add:
[code:1] PRED0 (IPHAS) = 0.1234D00[/code:1]- or whatever you need

I just checked with CS 1.3.3 and it works. Hope it helps. Could be interesting to see some results from your calculation.

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10 years 4 months ago #5554 by Torben
Replied by Torben on topic Re:Code Saturne Outlet pressure
Thinking it over again - I dont think there is a big difference between the reference pressure approach and the PRED0 approach when the fluid properties are indepedant of pressure. So if thats the case stick to the easier one.

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