Blackbody Radiation
This feature is only available in 3D.
The Blackbody Radiation node releases rays from selected boundaries with the following properties:
1
The rays are diffusely emitted from one side of the surface, meaning that the initial ray directions are random and their distribution follows Lambert’s cosine law,
2
If the Geometrical Optics interface has been set up to trace polychromatic light rays, the vacuum wavelength or frequency of the released rays is random and their distribution follows Planck’s Law, and
3
If ray intensity or power is solved for, the total source power is defined using the Stefan–Boltzmann law.
See Release for information on the Release Times and Initial Value of Auxiliary Dependent Variables sections.
Model Input
Enter a value or expression for the Temperature T (SI unit: K), which is used in the Stefan–Boltzmann law for ray power and the Planck equation to sample wavelength or frequency values. The default is 293.15 K. If the temperature has already been solved for in another physics interface, then it may be selected from the list.
Initial Position and Direction
Enter an integer value for the Number of rays per release N (dimensionless). The default is 1000. The released rays are always randomly distributed over the selected surfaces with uniform probability.
The Blackbody Radiation node always releases rays in random directions following Lambert’s cosine law, which states that the flux across a differential solid angle element is proportional to the cosine of the angle between that solid angle element and the wall normal direction. While the settings window for the Blackbody Radiation node is shown, the orientation of the surface normal is indicated by arrows shown in the Graphics window. You can reverse the direction of the surface normal by selecting or toggling the Reverse direction check box.
Blackbody Radiation Theory