# Volume fraction UDF in mixture model

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 April 2, 2013, 09:23 Volume fraction UDF in mixture model #1 New Member   wawa Join Date: Nov 2010 Posts: 24 Rep Power: 7 Hi everybody, Can I use C_VOF(c,pt[i]) in a UDF for the Multiphase Mixture model ? FLUENT is giving me 'ACCESS_VIOLATION' error... Can anybody suggest an alternative to get the volume fraction of a phase in my UDF ?, or even better, the pressure of a particular phase in the mixture ? Thanks wawa

 April 3, 2013, 01:47 #2 Senior Member   Paritosh Vasava Join Date: Oct 2012 Location: Lappeenranta, Finland Posts: 664 Rep Power: 15 Can you show your UDF please.

 April 3, 2013, 04:58 #3 New Member   wawa Join Date: Nov 2010 Posts: 24 Rep Power: 7 I'm basically trying to calculate the partial pressure of water-vapour in a mixture of air, liquid water and water-vapour. I'm using the mixture model, with evaporation-condensation, and the 'DEFINE_PROPERTY' is used to obtain the saturation temperature to use in the model. I need the partial pressure of water-vapour in order to calculate the saturation temperature (via an experimental equation). DEFINE_PROPERTY(sat_temp,c,t) { Thread *tm, **pt; real par_pres; real sat_temp; tm = THREAD_SUPER_THREAD(t); pt = THREAD_SUB_THREADS(tm); par_pres = C_VOF(c,pt[2])*C_P(c,t); /*pt[2] because 2nd secondary phase is water vapour*/ sat_temp = pow(par_pres,0.11); return sat_temp; } My issue is that I cannot access the volume fraction C_VOF(c,pt[2]) in FLUENT. THe code compiles well, but at initialisation, it gives me 'ACCESS VIOLATION' error. Can you help ?

 April 3, 2013, 09:08 #4 Senior Member   Paritosh Vasava Join Date: Oct 2012 Location: Lappeenranta, Finland Posts: 664 Rep Power: 15 I have doubt if you can use the macro C_VOF(c,pt[2]) with mixture model (Anyone?). That could be the issue. Can you test your code without 'C_VOF(c,pt[2])' and see if it works.

 April 3, 2013, 12:14 #5 New Member   wawa Join Date: Nov 2010 Posts: 24 Rep Power: 7 Yes, it does work without C_VOF... Is there another way to get the volume or mass fraction with the mixture model ?

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