[nitan9]

Hi,
I need to write a UDF function in which the heat transfer coefficient is a function of Temperature and it should be application only for dT/dt >0.

For Eg.
DEFINE_PROFILE(convection,thread,position)
{
face_t f;
real fc[ND_ND];
real temp_con,h,dT/dt;

begin_f_loop(f,thread,)
{
temp_con=F_T(f,thread);
if ( dT/dt>0)
h = -0.5T+10
else if (dT/dt < 0)
h = 5T+0.1;
F_PROFILE(f,thread,position)=h;
}
end_f_loop(f,thread)
}

Thanks in advance

[AlexanderZ]

Dt/dt macro -> C_T_G(c,t) - temperature gradient vector

Note that you can access vector components of each of the variables listed in
Table: Macros for Cell Gradients Defined in mem.h by using the integer index [i] for each macro listed in Table: Macros for Cell Gradients Defined in mem.h.
For example, C_T_G(c,t)[i] will access a component of the temperature gradient vector

The solver continually removes data from memory that it does not need. In order to retain the
gradient data (when you want to set up user-defined scalar transport equations, for example), you can
prevent the solver from freeing up memory by issuing the text command solve/set/expert and
then answering yes to the question, “Keep temporary solver memory from being freed?”
Note that when you do this, all of the gradient data is retained, but the calculation requires more
memory to run.