Average Temperature
 

Hi,

I am simulating a sub-channel flow (in a nuclear reactor), so I have 4 domains (fuel, gap, clad and fluid).
I have a volumetric heat generation into the fuel and I and to calculate the fluid average temperature by using a UDF.

I wrote something like that:

#include "udf.h"

DEFINE_TEMPERATURA(temp_ave_fluid)

{
Domain *d;
cell_t c;
Thread *tc;
ind ID = 30; */ ID of the domain fluid
d = Get_Domain(1);
real volume = 0.0;
real temper = 0.0;
real temperature_fluid;
tc = Lookup_Thread(d,ID);

begin_c_loop(c,tc)
{
volume = C_VOLUME(c,tc);
temper += C_T(c,tc)*C_VOLUME(c,tc);
vol_tot += volume;
tsum += temper
}
end_c_loop(c,tc)

temperature_fluid=tsum/vol_tot;

printf("\n Temperature sonde: %e K \n , temperature_fluid);

}

But I can not interpret the UDF, Fluent says:
"unterminated string or character constant"
"possible real start of unterminated constant"
"line 7: parse error"

Could someone helps me? Please

Thanks

Not sure what line 7 is in your code, but a couple of things:

1: I've never heard of the DEFINE_TEMPERATURA macro. Not sure what it is or what it does, if it even exists.
2: If you want to just calculate and print a variable, I'd suggest using DEFINE_ADJUST.
3: There's a spelling error in "Ind ID = 30;". It should read "Int ID = 30;".
4: Are you trying to calculate a volume-weighted average temperature? If so, don't need a UDF for that, you can just create a monitor for it.
5: If you do absolutely want a UDF for it, I think you're making a calculation error, as you're summing C_T(c,ct)*C_VOLUME(c,ct) twice. I'd suggest to just write "volume += C_VOLUME(c,ct) and delete the vol_tot and tsum calculations/variables.

But perhaps these suggestions are irrelevant as it could be that I misunderstand what you're trying to do. I understand it's a nuclear reactor, but I figure your fluid is in a separate domain/volume from the fuel rod and cladding, right? So is it the coolant's average temperature you want?

Dear Kevin,

Thank you for your response.

Actually I did some mistakes, thanks.

I really need to calculate the average temperature by UDF to use the information to perform a feedback to the fuel.

I am a little lost in UDF, I don't find a lot o material on internet to learn.

If I try to use DEFINE_ADJUST, Fluent says that I have only one argument, but it's not a error, and I also tried with DEFINE_ADJUST (temp_ave_fluid, domain).

Today my code is:

#include "udf.h"

DEFINE_EXECUTE_AT_END(temp_ave_fluid)
{
Domain *d;
cell_t c;
Thread *tc;
Int ID = 30;
d = Get_Domain(1);
real volume = 0.0;
real temper = 0.0;
real temperature_fluid;
tc = Lookup_Thread(d,ID);

begin_c_loop(c,tc)
{
volume += C_VOLUME(c,tc);
temper += C_T(c,tc)*C_VOLUME(c,tc);
}
end_c_loop(c,tc)

temperature_fluid=tsum/vol_tot;
printf("\n Temperature sonde: %e K \n , temperature_fluid);
}

But I keep having the same problems.

Thanks one again,
Felipe

Well, you need to close the string in your printf statement, as now you've only got the opening quotation mark ", but no accompanying closing one. So put a " after the second \n in the printf statement.

Also, I noticed in your old code you used */, but that signals end of comments. Start of comments is indicated by /*.

But outside of the syntax, what is it you're really trying to do? Because the macro to use depends on what you want to accomplish. I suggested DEFINE_ADJUST for just outputting information, but perhaps you need another one if you want to feed your volume weighted average temperature back to your simulation.

Kevin,

Thank you very much for your corrections.

But it still not working...

"#include "udf.h"

DEFINE_ADJUST(temp_ave_fluid)
{
Domain = Get_Domain(1);
cell_t c;
Thread *tc;
real volume = 0;
real temper = 0;
real temperature_fluid;
tc = Lookup_Thread(domain,fluid);

begin_c_loop(c,tc)
{
volume += C_VOLUME(c,tc);
temper += C_T(c,tc)*C_VOLUME(c,tc);

}
end_c_loop(c,tc)

temperature_fluid=temper/volume;
printf("\n Temperature sonde: %e K \n , temperature_fluid");

}"

And actually I have serious problems when Fluent try ti read it:


"cpp -I"C:\PROGRA~1\ANSYSI~1\v150\fluent\fluent15.0.7/src" -I"C:\PROGRA~1\ANSYSI~1\v150\fluent\fluent15.0.7/cortex/src" -I"C:\PROGRA~1\ANSYSI~1\v150\fluent\fluent15.0.7/client/src" -I"C:\PROGRA~1\ANSYSI~1\v150\fluent\fluent15.0.7/multiport/src" -I. -DUDF
ONFIG_H="<udfconfig-host.h>" "C:\Documents and Settings\Lasme\Desktop\UDF_Tmedio_fluido\qv_cos_03 _copia\Tmedio_fluido3.c"
C:\\Documents and Settings\\Lasme\\Desktop\\UDF_Tmedio_fluido\\qv_co s_03_copia\\Tmedio_fluido3.c:3: macro `DEFINE_ADJUST' used with just one arg
Error: C:\\Documents and Settings\\Lasme\\Desktop\\UDF_Tmedio_fluido\\qv_co s_03_copia\\Tmedio_fluido3.c: line 5: parse error.
Error: C:\\Documents and Settings\\Lasme\\Desktop\\UDF_Tmedio_fluido\\qv_co s_03_copia\\Tmedio_fluido3.c: line 6: parse error.
Error: C:\\Documents and Settings\\Lasme\\Desktop\\UDF_Tmedio_fluido\\qv_co s_03_copia\\Tmedio_fluido3.c: line 7: parse error.
Error: C:\\Documents and Settings\\Lasme\\Desktop\\UDF_Tmedio_fluido\\qv_co s_03_copia\\Tmedio_fluido3.c: line 8: parse error.
Error: C:\\Documents and Settings\\Lasme\\Desktop\\UDF_Tmedio_fluido\\qv_co s_03_copia\\Tmedio_fluido3.c: line 9: parse error.
Error: C:\\Documents and Settings\\Lasme\\Desktop\\UDF_Tmedio_fluido\\qv_co s_03_copia\\Tmedio_fluido3.c: line 10: parse error.
Error: C:\\Documents and Settings\\Lasme\\Desktop\\UDF_Tmedio_fluido\\qv_co s_03_copia\\Tmedio_fluido3.c: line 11: tc: undeclared variable
MPI Application rank 0 exited before MPI_Finalize() with status -1073741819
The fl process could not be started."

Do you not what it's wrong now? Please

Thanks,
Felipe

Did you try to go over the look up function directly?