In the industrial process of film casting, air can be blown on the film to heat or
cool it. You can model the effect of this in Ansys Polyflow. In general, the surface heat
flux 
is obtained as a combination of the following:
a constant heat flux
a heat transfer by convection characterized by a coefficient
and a reference temperature 
a heat transfer by radiation characterized by a coefficient
and a reference temperature 
The heat flux can be written as
 | (18–5) |
In polymer applications, however, the transfer through radiation is negligible with respect to the heat transfer by convection. Specification of the heat transfer coefficient applies for both sides of the film (the sum of the upper and lower heat transfer coefficients).