About Film Conditions

A film condition definition consists of these components:

• Transmission surface
• Reference temperature
• Film coefficient

Unlike a heat flux, which directly prescribes a constant flow of heat into or out of a surface, film conditions determine the flow of heat due to convection effects and differences between the temperature of a surface and the temperature of its surroundings (that is, the reference temperature). If the surface is the same temperature as its surroundings, no heat flow occurs. The film coefficient is a property of a surface that determines how quickly it transfers heat with its surrounding; the higher the film coefficient, the higher the resulting heat flux is.

Film conditions are available for steady-state heat transfer, transient heat transfer, coupled thermal-stress, coupled thermal-stress explicit, coupled thermal-electrical, and coupled thermal-electrical-stress steps. You can define various types of film coefficient and reference temperature. The film coefficient and reference temperature types usually match, but you can choose the types that best fit your simulation.

Film Coefficient / Reference Temperature	Description
Uniform value	One value is used throughout the model.
Mapped spatial data	A mapping table defines the value at each location, with a separate value for all areas outside the mapped region.
User-defined	A FILM user subroutine linked to the analysis case defines the film coefficient. The SINK parameter within the FILM user subroutine sets the reference temperature.
Film property	A predefined film coefficient that is a function of temperature and field variables.