# temperature and pressure dependent specific heat?

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 April 5, 2012, 05:51 temperature and pressure dependent specific heat? #1 New Member   Join Date: Apr 2012 Posts: 1 Rep Power: 0 How to add pressure dependence in DEFINE_SPECIFIC_HEAT? I'm doing with plasma, Cp varies with T and P drastically..... Thank you for any suggestion.

 April 5, 2012, 06:08 #2 Member   misagh Join Date: Apr 2012 Posts: 64 Rep Power: 7 hi.im not sure.if it was dependent to only T it was easy.but now with T and P dependence i think UDF will work.

 April 18, 2012, 12:16 specific heat func. of temperature #3 New Member   OscarD Join Date: Sep 2011 Posts: 4 Rep Power: 8 I'm working with plasma modeling and require thermodynamic properties of argon as a function of temperature (at least, but it should also be pressure dependant). I did a simple UDF for the specific heat, but it keeps giving me the same error once I try to initializate the calculation: "Warning: Incorrect Specific Heat value" the UDF is: DEFINE_SPECIFIC_HEAT(SpecHeat_Ar,T,Tref,h,yi) { real SpecHeat,a1,b1,c1,a2,b2,c2; real x = T/1000.; /*input temp in kK*/ a1 =8.064;b1 =13.92;c1 =2.721;a2 =2.907;b2 =28.19;c2 =19.67; SpecHeat = a1*exp(-pow(((x-b1)/c1),2.)) + a2*exp(-pow(((x-b2)/c2),2.)); SpecHeat=SpecHeat/1000.; /* the specific heat material property value is in [J/kg-K]*/ return SpecHeat; } I used similar eqs for thermal conductivity and viscosity. Does anybody what could be wrong?. Thanks

 December 16, 2012, 03:10 #4 Senior Member   SSL Join Date: Oct 2012 Posts: 226 Rep Power: 8 I have the same problem when injected particles get vaporized, the warning "incorrect specific heat value" occures. Any solution?

 December 18, 2012, 10:46 #5 Member   Join Date: Dec 2012 Posts: 82 Rep Power: 7 Hi I made a Service Request and Fluent answered that it is NOT possible to write an UDF with pressure-dependend Specific Heat right now. I hope they will change this in the future. I tried it on my own, DEFINE_PRPERTY works fine but DEFINE_SPECIFIC_HEAT is crap. Use the USER FORTRAN in CFX

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