strange temperature rise
 

in my case firstly i using constant velocity every thing is normal the cooling temperature isn't rising but when i use a udf for velocity the temperature of the cooling fluid rise to the temperature of the main fluid ( attaching pic) which isn't logic as the velocity used in the first time step is exactly equal to the constant one (i'm attaching the udf also)


the udf :
#include "udf.h"

DEFINE_PROFILE(unsteady_x_velocity12, thread, position)
{
face_t f;
real tm = CURRENT_TIME;
begin_f_loop (f,thread)
{
if(tm < 0.1)
{
F_PROFILE (f,thread,position)= 8.479;
}
if(tm > 0.1)
{
F_PROFILE (f,thread,position)= 1.357;
}
if(tm > 0.2)
{
F_PROFILE (f,thread,position)= 8.479;
}
if(tm > 0.3)
{
F_PROFILE (f,thread,position)= 1.357;
}
if(tm > 0.4)
{
F_PROFILE (f,thread,position)= 8.479;
}
if(tm > 0.5)
{
F_PROFILE (f,thread,position)= 1.357;
}
if(tm > 0.6)
{
F_PROFILE (f,thread,position)= 8.479;
}
if(tm > 0.7)
{
F_PROFILE (f,thread,position)= 1.357;
}
if(tm > 0.8)
{
F_PROFILE (f,thread,position)= 8.479;
}
if(tm > 0.9)
{
F_PROFILE (f,thread,position)= 1.357;
}
if(tm > 1.0)
{
F_PROFILE (f,thread,position)= 8.479;
}
if(tm > 1.1)
{
F_PROFILE (f,thread,position)= 1.357;
}
}
end_f_loop (f,thread)
}