[Carlo]

Hi to all. Here's my problem:
I'm dealing with coal combustion; in my case I have also gas recirculation. In particular, I have an UDF that computes the outlet NOx mass fraction; this value must be imposed in an inlet (due to the recirculation). Any idea to do it? Here's my UDF:

#include "udf.h"

DEFINE_ADJUST(noflux, domain)
{
int zone_ID = 4;
Thread *t = Lookup_Thread(domain,zone_ID);
face_t f;
real summ=0.;
real m;
real sumnox=0.;
real mnox;
real nox;
real sumarea=0.;
real area;
real Cnox;
real NV_VEC (A);
begin_f_loop(f,t)
{
F_AREA(A,f,t);
nox=C_POLLUT(f,t,1); /*Pollutant mass fraction Kg(NO)/Kg(g) in each face*/
mnox=F_U(f,t)*F_R(f,t)*NV_MAG(A)*6.28*nox; /*[Kg(NO)/Kg(g)]*[Kg(g)/s]=[Kg(NO)/s] in each face*/
sumnox += mnox; /*Kg(NO)/s in the whole domain*/
m=F_U(f,t)*F_R(f,t)*NV_MAG(A)*6.28;
summ += m; /*Kg(g)/s in the whole domain*/
area=NV_MAG(A)*6.28;
sumarea += area;
}
end_f_loop(f,t)
Cnox=sumnox/summ; /*[Kg(NO)/s]/[Kg(g)/s]*/
printf("massf: %g,%g,%g,%g\n", summ,sumnox,Cnox,sumarea);
}

real Cnox; /*Why do I have to declare it twice? Does fluent hold it?*/
DEFINE_PROFILE(noflux_b, t, nv)
{
face_t f;
begin_f_loop(f, t)
{
F_PROFILE(f,t,nv) = Cnox;
}
end_f_loop(f, t)
}

The ID=4 corresponds to the outlet. Am I doing it right? After having compiled and loaded the UDF, I hooked the noxflux function (DEFINE_ADJUST) whereas in the boundary condition of the considered inlet, in the NO mass fraction menu I set the noxflux_b function (DEFINE_PROFILE).
I'm not sure about this way to proceed. Indeed I don't know if the second DEFINE holds the Cnox variable value or if It clears it. I think this because if I don't declare "real Cnox" before starting the second DEFINE, I get the error "undeclared...etc", as if it had seen the Cnox variable for the first time! Any Idea?
Thanks!!