Interfaces and Features for Radiation in Transparent Media
The following table recalls the functionalities available for the modeling of radiative heat transfer in transparent media.
Table 3-15: Modeling of Heat Transfer by Radiation in transparent media.
 
Surface-to-Ambient
Surface-to-Surface
Description
 Physical and modeling assumptions
Refractive index of domain
n=1
Any, uniform
Diffuse reflection
Yes
Yes
Specular reflection
No
With Ray shooting
Transmission
No
With Ray shooting
Refraction at interfaces
No
With Ray shooting
Shadowing effects in view factor computation
No
With Hemicube or Ray shooting
Wavelength dependence of surface properties
No
Yes (Solar and ambient / Multiple spectral bands)
No (Constant)
Directional dependence of surface properties
No
With Ray shooting
Dimension of the domain
3D, 2D axi, 2D, 1D axi, 1D
3D, 2D axi, 2D, 1D axi, 1D
Example in Application Library
Continuous Casting
Chip Cooling
 License, interfaces and features
License requirement
COMSOL Multiphysics /
Heat Transfer Module
Heat Transfer Module
Interfaces
Heat Transfer (ht)
Heat Transfer in Shells (htlsh)
Surface-to-Surface Radiation (rad)
Domain features
Out-of-Plane Radiation (1)(2)
Opacity
Boundary features
Surface-to-Ambient Radiation
Dielectric Window
Diffuse Mirror
Diffuse Surface
Opaque Surface
Radiation Shield
Refractive Interface
Specular Mirror
Semitransparent Surface
Initial Values
Prescribed Radiosity
Radiation Group
Edges/Point features
Surface-to-Ambient Radiation(1)
N/A
Global features
N/A
External Radiation Source (3)
Symmetry for Surface-to-Surface Radiation (4)
Multiphysics features
N/A
Heat Transfer with Surface-to-Surface Radiation
 Numerical aspects
Numerical cost
Low
Medium to high
Radiation variables
None
Surface radiosity J (if constant wavelength), J1, J2 (if solar and ambient wavelengths),
J1, …, Jn (if multiple wavelengths)
(1) Only with the Heat Transfer Module
(2) Only in 2D and 1D components
(3) Only in 3D and 2D components
(4) Only in 3D, 2D axi, and 2D components