# REAL GAS UDF

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 August 30, 2006, 17:38 REAL GAS UDF #1 brian Guest   Posts: n/a I'm modeling a blowdown from a high pressure vessel (7 MPa) to ambient conditions, that go through a nozzle at choked conditions. Does anyone know of a way to model the density accurately, accounting for compressibility? Do you have a UDF? Thanks in advance.

 September 1, 2006, 04:19 Re: REAL GAS UDF #2 Martin Skov Rasmussen Guest   Posts: n/a There's a Redlich-Kwong Equation of State based UDF available from Fluent UDF archive, which can be used to model real gases. This may help you...

 September 4, 2006, 09:07 SRK ? #3 ABEL Guest   Posts: n/a Please wich version of fluent contain the SRK equation of state I am searching it to model h2/o2 combustion ???

 September 5, 2006, 00:47 Re: SRK ? #4 Martin Skov Rasmussen Guest   Posts: n/a The UDF is available from the UDF archive at fluentusers.com, and it is a Redlich-Kwong Real Gas UDF, the Soave modified version. However, for H2/O2 combustion I doubt that you will need a real gas model. Have you tried to calculate some compressability factors in order to determine the deviation from an ideal gas at you relevant conditions?

 September 6, 2006, 08:32 Re: SRK ? #5 Abel Guest   Posts: n/a Dear Skov, these are my operating conditions GH2 P=70 bars , T = 287 K GO2 P=70 bars , T = 100 K A+

 September 6, 2006, 08:47 Re: SRK ? #6 Martin Skov Rasmussen Guest   Posts: n/a What are the respective mole/mass fractions or flow rates -the ratio between H2 and O2. By the way a real gas model should be available with the coupled solver, thus you do not need to go into UDF modeling of the real gas state...