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-   -   Udf function average temp inlet - outlet (http://www.cfd-online.com/Forums/fluent/85807-udf-function-average-temp-inlet-outlet.html)

erodv March 7, 2011 15:33

SOLVED:Udf function average temp inlet - outlet
 
Hello,

I would appreciate if somebody take a look in the UDF and give me some advices. I am trying to get the average temperature at the outlet of a pipe, and after some manipulations use it in the pressure inlet of the next time step. It compiles and the simulation runs up to the first time step. It starts with reversed flow then just after the first time step prints Temperature limited to 1 in the domain 1. Tavg prints -nan.

Thanks

DEFINE_EXECUTE_AT_END(Temp_inlet)
{
Domain *d;
real Temp_t;
real area;
real area_tot;
real tavg;
real A[ND_ND];
Thread *t;
face_t f;
d=Get_Domain(1);

t=Lookup_Thread(d,11);

begin_f_loop(f,t)
{
area = F_AREA(A,f,t);
Temp_t += F_T(f,t);
area_tot += area;
tavg += Temp_t*area;
}
end_f_loop(f,t)
tavg /= area_tot;
tavg_tot1=tavg;
printf("\n Tavg = %f\n",tavg_tot1); /*output -nan*/
}

DEFINE_PROFILE(Temp_inlet,t,i)
{
face_t f;
real time;
real current_time;
time=CURRENT_TIMESTEP;
current_time=CURRENT_TIME;

if (current_time >=10.)
{
begin_f_loop(f,t)
{
F_PROFILE(f,t,i)=((fabs(flow_tot)*(tavg_tot-tavg_tot1)*time)/15.)+tavg_tot1;
}
end_f_loop(f,t)
}
else
{
begin_f_loop(f,t)
{
F_PROFILE(f,t,i)=288.16;
}
end_f_loop(f,t)
}
}

Amir March 7, 2011 16:08

Hi,
I think the problem is in your face loop, substitute this and check. hope that help you:
Quote:

tavg=0;
area_tot=0;
begin_f_loop(f,t)
{
F_AREA(A,f,t);
AREA=NV_MAG(A);
area_tot += AREA;
tavg +=F_T(f,t)*AREA;
}
end_f_loop(f,t)
tavg /= area_tot;

erodv March 7, 2011 20:54

Solved
 
Thanks Amir, I did your proposed changes and it worked, this thread has been solved :).


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