Radiation Conductivity for a Random Void-Solid Medium with Diffusely Reflecting Surfaces
Material type: ArticleDescription: 725-734 pISSN:- 0017-9310
Item type | Current library | Call number | Vol info | Status | Date due | Barcode |
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Articles | Periodical Section | Vol.33, No.4 (April 1990) | Available |
A variational principle is formulated for radiant heat transfer through the void spaces and conduction in the solid, of an arbitrary void-solid system with diffusely reflecting surfaces. Variational upper bounds on the effective conductivity of a void-solid suspension are expressed in terms of certain averages characterizing the random geometry. A radiation conductivity upper bound, calculated for a model porous medium generated by randomly placed, overlapping spheres, is compared with well-known results from kinetic theory and radiant heat transport. The variational principle provides a means to obtain useful estimates and upper bounds on the thermal radiation conductivity, that include multiple and anisotropic diffusive scattering in a bed of large particles.