Radiation—Introduction
Thermal radiation, along with convection and conduction, is one of the three principal mechanisms of heat transfer. Radiation is the emission of a spectrum of electromagnetic waves from all matter whose temperature is greater than absolute zero. Unlike the flow-driven heat convection and the conduction that use direct physical contact, thermal radiation does not require the presence or participation of matter for radiative heat to be transferred through a vacuum, or any solid or fluid transparent medium.
In a thermal system, radiation can be significant when the radiative heat flux is large compared to the heat transfer rate due to convection, conduction, or both convection and conduction. Usually this occurs at high temperatures where the 4th order dependence of the radiative heat flux on the body temperature implies that radiation will dominate the heat transfer process. Common applications of radiation include the following:
• Surface-to-surface radiant heating or cooling
• Coupled heat transfer of radiation, convection, and conduction
• Radiation through windows and cabin heat transfer
• Radiation in glass processing, glass fiber drawing, and ceramic processing
• Radiative heat transfer from flames
In CFA simulations, the goal of radiation modeling is to solve the radiative transport equation. Thus, you need to obtain the radiative source term for the governing equation of the total energy conservation and the radiative heat flux at the walls.
Radiation is a module in Creo Flow Analysis. To access this module, follow the steps listed below:
1. Right-click 
Physics and click Select Physics Models. The Physical Model Selection dialog box opens.
Physics and click Select Physics Models. The Physical Model Selection dialog box opens.2. Select Radiation from Available Modules. In the Flow Analysis Tree, under Physics, Radiation is added.
See below for a description of items in the Radiation module:
• Definitions—Terms used in radiation modeling.
• Physics—Definitions, terminology, constants, models and methods used in radiation modeling.
• Conditions—Conditions specified for the entities such as boundaries, interfaces, volumes, and the outputs from the module.