[guti]

I want to apply solar heat flux on parabolic trough collector’s absorber tube with convection and radiation in 2D. Already, I have created my first UDF and faced big problem. One thing, I do not understand how to read the face wall temperature and its distribution. Can anyone help me? The code is here. When I interpreted it, it says face_tf; is undeclared variable. Please tell me what I have missed out. Thank you for your cooperation.
#include"udf.h"
#include"mem.h"
#define sigma 5.6697*10^-8
#define epsilon 0.1
#define H_air 8.52 /* convective heat transfer coefficient*/
#define T_air 298
#define T_sky 255
DEFINE_PROFILE(heat_flux, thread, i)
{
real x[ND_ND] ; /* this will hold the position vector*/
real y;
real z;
real r;
real T_abs;

cell_tc;
Thread*t0;
face_tf;
begin_f_loop (f, thread)
{
c0=F_C0(f,t);
t0=F_C0_THREAD(f,t);
T_abs=F_T(f,t);
F_CENTRIOD (x,f,thread);
y=x[1];
z=x[2];
r=pow((pow(y,2) +pow(z,2)),0.5);
F_PROFILE (f, thread, i) =H_air*(T_abs-T_air) +(epsilon*sigma*(T_abs+T_sky) *(pow(T_abs,2) +pow(T_sky,2))) *(epsilon*sigma*(pow(T_abs,4) +pow(T_sky,4)))
}
end_f_loop(f, thread)
}

[guti]

Few correction on the statements.

I want to apply solar heat flux on rotating circular tube with convection and radiation in 3D. Can I combine DEFINE_CG_MOTION and DEFINE_PROFILE macros or which one can I use for the problem? Can anyone help me? Please tell me how can I proceed it? Thank you for your cooperation.