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-   -   Inlet pressure (http://www.cfd-online.com/Forums/fluent-udf/76596-inlet-pressure.html)

alikami May 30, 2010 12:38

Inlet pressure
 
I simulated over expanded nozzle at 1 bar ambient , steady state with mass flow rate inlet condition. super sonic gauge presure i used 70 bar
now i wanted to change inlet pressure with respect to time .
i give in put using
#include "udf.h"
DEFINE_PROFILE(unsteady_pressure, thread, position)
{
float t, pressure;
face_t f;

begin_f_loop(f, thread)
{
t = RP_Get_Real("flow-time");
pressure = 200000+300*t;
F_PROFILE(f, thread, position) = pressure;
}
end_f_loop(f, thread)
}

and solved for 10 milli second
and saved file..
when i look at result no change in pressure , remains 70 bar
I did change the pressure inlet from constant to ydf pressure
someone can help
Regards
Ali

om1234 May 31, 2010 19:15

maybe it could be helpful

#include "udf.h"

DEFINE_PROFILE(unsteady_pressure, thread, position)
{
face_t f;

begin_f_loop(f, thread)
{
real t = RP_Get_Real("flow-time");
F_PROFILE(f, thread, position) =200000+300*t;
}
end_f_loop(f, thread)
}

coglione June 2, 2010 05:34

If I understand you right, you are using a mass-flow inlet BC. In this case supersonic/initial gauge pressure is only used for initializing the solution and your udf will not have any effect for the rest of the computation.

cherrs

alikami June 2, 2010 08:01

means i should give mass flow inlet using udf?
can you help how?
also if i have particles in flow how to give it using udf also?
plz help
Regards
ali


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