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-   -   Volume fraction UDF in mixture model (http://www.cfd-online.com/Forums/fluent-udf/115559-volume-fraction-udf-mixture-model.html)

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 ?

Thanks
wawa

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).

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 ?

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 ?


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