[mariam.sara]

Dear all
I tried to interpret the below UDF for specific heat Cp in terms of liquid fraction that used in Solidification/Melting model the UDF as below:

#include "udf.h"
DEFINE_SPECIFIC_HEAT(specificheat, T, Tref, h, yi)
{
#if !RP_HOST
real cpm,dt;
Tref=308;
real cps = 1800.0;
real cpl = 2400.0;
real lat = 160000.0;
real LIQF = C_T(cell, thread);
dt=exp(-T*(T-Tref)*(T-Tref)/4.0)/sqrt(4.0*3.14);
cpm =cps+(cpl-cps)*C_LIQF(c,t)+lat*dt;
*h = cpm*(T-Tref);
return cpm;
#endif
}

The problem I got the following errors with unknown reason:

Error: C:/Users/DELL/AppData/Local/Temp/cp.c.32836.11.c: line 7: parse error.
Error: C:/Users/DELL/AppData/Local/Temp/cp.c.32836.11.c: line 8: parse error.
Error: C:/Users/DELL/AppData/Local/Temp/cp.c.32836.11.c: line 9: parse error.
Error: C:/Users/DELL/AppData/Local/Temp/cp.c.32836.11.c: line 10: parse error.
Error: C:/Users/DELL/AppData/Local/Temp/cp.c.32836.11.c: line 12: cps: undeclared variable

Any suggestions, please?
Mariam

[vinerm]

DEFINE_SPECIFIC_HEAT is not executed at cell level like DEFINE_PROPERTY. That's why it requires a separate function while most of the other properties can be modeled using DEFINE_PROPERTY. It executes at material level and does not have access to cell and thread. C_T returns temperature of a cell but that is already available in form of T. If you are solving for species transport, then their mass fractions are available as yi. But you cannot access C_LIQF because its arguments are not available.

Lastly, you cannot interpret it. It must be compiled.

[mariam.sara]

Originally Posted by vinerm

DEFINE_SPECIFIC_HEAT is not executed at cell level like DEFINE_PROPERTY. That's why it requires a separate function while most of the other properties can be modeled using DEFINE_PROPERTY. It executes at material level and does not have access to cell and thread. C_T returns temperature of a cell but that is already available in form of T. If you are solving for species transport, then their mass fractions are available as yi. But you cannot access C_LIQF because its arguments are not available.

Lastly, you cannot interpret it. It must be compiled.

I do not use the species model just the solidification and melting model?
Do you mean I need to use compile to implement this UDF?

regards

[vinerm]

You need to make changes to the UDF and then compile it. You cannot use C_T and C_LIQF. Those are not available within specific heat function.

[mariam.sara]

Actually I am not that familiar with UDF hence I have no idea what to do with C_T and LIQF? any suggestions are highly appreciated?

Regards

[vinerm]

C_T and C_LIQF are macros that return temperature and liquid fraction in a cell. However, cell temperature is already available as T, in case you need it to define specific heat. But you cannot access C_LIQF even if you need it. It all depends on the equation you have for specific heat. Does the equation require value of liquid fraction or temperature or not?

[mariam.sara]

Originally Posted by vinerm

C_T and C_LIQF are macros that return temperature and liquid fraction in a cell. However, cell temperature is already available as T, in case you need it to define specific heat. But you cannot access C_LIQF even if you need it. It all depends on the equation you have for specific heat. Does the equation require value of liquid fraction or temperature or not?

I think the equation function of both here is the equation attached

[vinerm]

Rest is clear but what are and ?

[mariam.sara]

f(T) is the liquid fraction
deltaT is constant as 2 C

[vinerm]

That means = C_LIQF, however, you cannot access C_LIQF within DEFINE_SPECIFIC_HEAT. So, you have to define liquid fraction, somehow, in terms of T. Anyway, it is a function of T, that's why .