CFD Online Discussion Forums

CFD Online Discussion Forums (
-   Fluent UDF and Scheme Programming (
-   -   Volume fraction UDF in mixture model (

wawa April 2, 2013 09:23

Volume fraction UDF in mixture model
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 ?


vasava April 3, 2013 01:47

Can you show your UDF please.

wawa April 3, 2013 04:58

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).

Thread *tm, **pt;
real par_pres;
real sat_temp;
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 ?

vasava April 3, 2013 09:08

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.

wawa April 3, 2013 12:14

Yes, it does work without C_VOF...
Is there another way to get the volume or mass fraction with the mixture model ?

All times are GMT -4. The time now is 19:09.