Annals of the Assembly for International Heat Transfer Conference 13

ISBN 1-56700-225-0 / CD 1-56700-226-9

Year 2006

C.-Y. Wu
National Cheng Kung University, Tainan, Taiwan

In this work, the discrete ordinates method has been adapted to solve transient radiative transfer in an anisotropically scattering slab with a spatial variable refractive index. The medium considered has a refractive index increasing in the direction of irradiation and is exposed to a short laser pulse at one of the boundaries. The time-resolved hemispherical reflectance and transmittance of the slab are obtained for a variety of optical thicknesses, scattering albedos, scattering phase function coefficients and gradients of refractive index. The discrete ordinates method adapted for transient radiative transfer has been proved to be effective and capable of generating accurate results. The time-resolved transmittance has a peak mainly due to the direct pulse and a plump tail due to the scattered radiation. The former appears later for the case with a larger refractive index, because the radiation energy propagates in a smaller speed in a slab with a larger refractive index. The latter may have a local maximum, when the scattering is strong. The variable refractive index may have contribution to the scattering, because the gradient of refractive index makes radiation stream in a curve path and increases the internal reflection. Thus, the local maximum increases with the increase of the gradient of refractive index. It is found that the reflectance of the slab decreases with the increase of the gradient of refractive index. The reflectance curve eventually merges with the corresponding transmittance curve as the time increases. The merging process takes more time for the case with a lager gradient of refractive index. Finally, it is found that the influence of anisotropically scattering on the time-resolved transmittance increases with the increase of the gradient of refractive index.

RAD-12 pages DOI: 10.1615/IHTC13.p4.120 Download article

Article price - $35.00

<< Previous article   Next article >>