# how to implement a Real gas law in fluent?

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 July 2, 2013, 04:03 how to implement a Real gas law in fluent? #1 Member   Join Date: Oct 2011 Posts: 37 Rep Power: 14 Hi. I’m simulating two-phase flow with combustion inside a closed volume. In fluent the density of the compressible gas phase is calculated by using “ideal gas law”. I want to use ‘’real gas law’’, for example Nobel-Abel law. But I don’t know how to implement this new law into fluent via UDF. Does anyone have an idea how I can do this? Regards,

 July 2, 2013, 07:30 #2 Member   Yash Ganatra Join Date: Mar 2013 Posts: 67 Rep Power: 13 Go to Materials, then from Density tab select Real Gas but i don't think Nobel Abel Law is there. There are other options. If you want to stick to Nobel Abel Law, then you will have to write a user defined function. (UDF) Yash

 July 4, 2013, 02:24 #3 Member   Join Date: Oct 2011 Posts: 37 Rep Power: 14 Hi Yash, thanks for your reply. Yes I want to use Nobel-Abel Law, and I can easily write an UDF for that. But the problem is in fluent if we use a Nobel-Abel Law instead of Ideal gas law, we should change a few other parameters such as the sound speed, the entropy and some Derivatives such as the partial derivative of density with respect to pressure at constant temperature. So the density law and the sound speed will be incorporated through the material panel. But for the others parameters I didn't find a way to incorporate them into fluent!!!! Regards,

 July 4, 2013, 03:14 #4 Member   Yash Ganatra Join Date: Mar 2013 Posts: 67 Rep Power: 13 Just go through Define Property Macro in FLUENT UDF and see if such changes can be incorporated through UDF

 July 4, 2013, 03:16 #5 Member   Yash Ganatra Join Date: Mar 2013 Posts: 67 Rep Power: 13 See DEFINE PROPERTY macro in UDF and check if such changes can be incorporated via a UDF. Could you kindly tell which problem are you working on? Yash

 November 13, 2015, 17:28 #6 Senior Member   navid Join Date: Jan 2010 Posts: 110 Rep Power: 16 Hi NAD, Were you able to solve your problem? If so could you please tell me how did you implemented the real gas udf in Fluent?

 Tags compressiblity, ideal gas law, two-phase flow, udf