Emittance of Semi-Infinite Absorbing and Isotropically Scattering Medium with Refractive Index Greater Than Unity
An approximate solution is presented for the integrodifferential equation that governs the radiant intensity and the source function within a semi-infinite absorbing-scattering medium with an index of refraction different from unity. The exponential kernel substitution has been used to develop a closed form analytical expression for the directional emittance as a function of the refractive index and the scattering albedo. The directional and the hemispherical emittances are presnted for a refractive index range between 1 and 2 for scattering albedo between 0 and 1. The results indicate that these emittances of a medium with a refractive index larger than unity can be either smaller, because of interface reflection, or larger because of scattering, than that associated with a medium of a unity index of refraction. A generalized graph is presented from which an approximate value for the directional emittance can be obtained for a wide range of optical conditions.
B. F. Armaly et al., "Emittance of Semi-Infinite Absorbing and Isotropically Scattering Medium with Refractive Index Greater Than Unity," AIAA Journal, American Institute of Aeronautics and Astronautics (AIAA), Jan 1973.
The definitive version is available at https://doi.org/10.2514/3.50617
Mechanical and Aerospace Engineering
Article - Journal
© 1973 American Institute of Aeronautics and Astronautics (AIAA), All rights reserved.