Thank you to all the people that helped me in these days. I'm still having problems with my UDF; now i post it all :

/************************************************** ********************

mut/mu profile

************************************************** *********************/

#include "udf.h"

/* profilo per il rapporto di viscosità turbolento */

DEFINE_PROFILE(mut_su_mu_profile, t, i)

{

real cf, utau, knw, kext, Kturb, mix, Epsilon;

real y, delta, uext, x[ND_ND], viscin, iext, cmu, vkc;

face_t f;

/*costanti*/

#define VISCIN 4.e-05 /*mu*/

#define Iext 0.01

#define uext 1.0

#define delta 0.5

#define CMU 0.09

#define VKC 0.41

cf = 0.045/pow(uext*delta/VISCIN,0.25);

knw=(pow(uext,2.)/sqrt(CMU))*cf/2.;

kext=(3./2.)*pow(uext,2.)*pow(Iext,2.);

begin_f_loop(f, t)

{

F_CENTROID(x,f,t);

y=x[2];

if (y <= delta)

Kturb=knw+y/delta*(kext-knw);

else

Kturb=kext;

if (VKC*y < 0.085*delta)

mix=VKC*y;

else

mix=0.085*delta;

Epsilon=pow(CMU,0.75)*pow(Kturb,1.5)/mix;

F_PROFILE(f,t,i)=F_R(f,t)*(CMU/VISCIN)*pow (Kturb,2.0)/Epsilon;

}

end_f_loop(f,t)

}

/************************************************** ********************

UDF for specifying a steady-state velocity profile boundary condition

************************************************** ********************/

DEFINE_PROFILE(inlet_x_velocity, thread, index)

{

real x[ND_ND];

real y;

real ydel;

real uset;

face_t f;

begin_f_loop(f, thread)

{

F_CENTROID(x,f,thread);

y = x[2];

if (y < delta)

y = x[2];

else

{

y = delta;

}

F_PROFILE(f, thread, index) = pow(y/delta,1./7.);

}

end_f_loop(f, thread)

}

/************************************************** ******************

udf_source_term.c line 90 UDF per il calcolo del source term (only 3D)

************************************************** ******************/

real Volume;

real ALPHA;

real XMIN, XMAX, YMIN, YMAX, ZMIN, ZMAX;

real Xg, Yg, Zg, dist;

real ny;

real d;

real d1;

real d2;

real dx, dy, dz;

real p1;

real p2;

real p3;

real xc[3];

real bar[3];

real xc1[3];

real x[3];

real x1[3];

int n;

DEFINE_ON_DEMAND(cell_select)

{

Domain *domain;

cell_t c;

Thread *t;

#define XMIN 1

#define XMAX 3.1

#define YMIN 14

#define YMAX 14

#define ZMIN 0

#define ZMAX 0.3

#define ALPHA 10

/*Calcolo del baricentro del MVG*/

p1=XMAX-XMIN;

p2=YMAX-YMIN;

p3=ZMAX-ZMIN;

Xg=p1/2+XMIN;

Yg=p2/2+YMIN;

Zg=p3/2+ZMIN;

bar[0]=Xg;

bar[1]=Yg;

bar[2]=Zg;

/*Valori iniziali per il confronto del ciclo if sulle celle*/

d=10;

d1=0;

domain = Get_Domain(1);

thread_loop_c(t,domain)

{

begin_c_loop(c,t)

{

C_CENTROID(xc,c,t);

dist=sqrt(pow((xc[0]-bar[0]),2)+pow((xc[1]-bar[1]),2)+pow((xc[2]-bar[2]),2));

if ( dist < d )

{

d=dist;

C_CENTROID(xc1,c,t);

for (n=0; n <= cell_type_nnodes[(int)C_TYPE(c,t)]; n++)

{

ny=NODE_Y(n);

d2=fabs(ny-bar[1]);

if (d2>d1)

{

d1=d2;

}

}

}

}

end_c_loop(c,t)

}

/*Calcolo del volume totale delle celle da selezionare*/

dx=(XMAX-XMIN)/2;

dy=d1/2;

dz=(ZMAX-ZMIN)/2;

Volume=0;

thread_loop_c(t,domain)

{

begin_c_loop(c,t)

{

C_CENTROID(x,c,t);

if ( fabs ( x[0] - bar[0] ) < dx )

{

if ( fabs ( x[2] - bar[2] ) < dz )

{

if ( fabs ( x[1] - xc1[1] ) < dy )

{

Volume=Volume+C_VOLUME(c,t);

}

}

}

}

end_c_loop(c,t)

}

}

/*PROVA INIZIALIZZAZIONE CAMPO*/

DEFINE_INIT(init_func, domain)

{

cell_t c;

Thread *t;

thread_loop_c (t,domain)

{

begin_c_loop_all (c,t)

{

C_CENTROID(x,c,t);

if ( fabs ( x[0] - bar[0] ) < dx )

{

if ( fabs ( x[2] - bar[2] ) < dz )

{

if ( fabs ( x[1] - xc1[1] ) < dy )

{

C_U(c,t)=100/Volume;

}

else

C_U(c,t)=0;

}

}

}

end_c_loop_all (c,t)

}

}

I wrote this UDF to set the boundary profiles at the inlet and to compute a source term for the x-mom eqn. At this stage there isn't the source term because i only want to know if i've selected the right cells where to put it in, so i wrote the DEFINE_INIT to do this check (after the initialization i will plot a velocity contour). The profiles already worked alone in an other UDF so i think the problem is not there. WHEN I INTERPRET THIS FILE, IT WORKS. After that the file has been interpreted i hook the on_demand routine and i have this error:

Error: FLUENT received fatal signal (ACCESS_VIOLATION) 1. Note exact events leading to error. 2. Save case/data under new name. 3. Exit program and restart to continue. 4. Report error to your distributor. Error Object: ()

but the initialization works (i need the on demand first). Obviously if i put all together in a DEFINE_INIT macro i have the same error. After this i started the debug of my UDF cutting a lot of parts and i discovered that when i try to run the on_demand the variables that i define in it are not read in the right way, so if i write:

#define a 1;

doesn't read it and say me that "a = a very big number that i don't remember" (i checked it with a printf command)

So now i'm going crazy because i don't know how to proceed. Any kind of help needed...please.

Thank you

Some news, maybe someone can help me:

I debugged all the UDF and i founded that the problem is the C_CENTROID(x,c,t) command, when i use it i have the fatal error. So i looked inside the metric.h file to see how is build the function C_CENTROID(x,c,t). Doing this i discovered that in this function is used the c_node_loop macro that gived me problems in the last days. Now i would try to see how is build this function inside fluent but i'm not able to do it because i can't find it anywhere. Do someone of you knows where is the relative "something.h" file in which is defined the macro c_node_loop? Or anyway someone knows what is the problem with my UDF?

Thanks a lot