The dispersion relation for an electromagnetic wave is obtained in particulate media using effective field approximation (EFA) and quasi-crystalline approximation (QCA). Due to multiple and dependent scattering the density of states, phase velocity and group velocity of photons are modified. Modification of these parameters modifies the Planck blackbody equilibrium radiation intensity and emissive power. Results show that EFA can accurately capture the dependence of density of states, phase velocity, and the group velocity on volume fraction of scatterers whereas QCA can capture the dependence of effective attenuation as well as density of states, phase velocity, and the group velocity. Comparisons of the temperature, heat flux, and effective attenuation are made between EFA, QCA, and work done by C. L. Tien and co-workers. Results show that heat flux and temperature predictions made by models in the literature for multiple and dependent scattering are not correct as these models do not take the modification of the equilibrium intensity into account. Finally we introduce a new model called dependent effective field approximation (DEFA) which accurately captures the effect of volume fraction on the equilibrium intensity and effective attenuation.
BT - J. Heat Transfer DA - 03/2005 DO - 10.1115/1.1928912 LA - eng M1 - 8 N2 -The dispersion relation for an electromagnetic wave is obtained in particulate media using effective field approximation (EFA) and quasi-crystalline approximation (QCA). Due to multiple and dependent scattering the density of states, phase velocity and group velocity of photons are modified. Modification of these parameters modifies the Planck blackbody equilibrium radiation intensity and emissive power. Results show that EFA can accurately capture the dependence of density of states, phase velocity, and the group velocity on volume fraction of scatterers whereas QCA can capture the dependence of effective attenuation as well as density of states, phase velocity, and the group velocity. Comparisons of the temperature, heat flux, and effective attenuation are made between EFA, QCA, and work done by C. L. Tien and co-workers. Results show that heat flux and temperature predictions made by models in the literature for multiple and dependent scattering are not correct as these models do not take the modification of the equilibrium intensity into account. Finally we introduce a new model called dependent effective field approximation (DEFA) which accurately captures the effect of volume fraction on the equilibrium intensity and effective attenuation.
PB - American Society of Mechanical Engineers PY - 2005 EP - 903–910 T2 - J. Heat Transfer TI - Modification of Planck Blackbody Emissive Power and Intensity in Particulate Media Due to Multiple and Dependent Scattering VL - 127 ER -