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ISSN Online: 2377-424X

ISBN Print: 0-89116-559-2

International Heat Transfer Conference 8
August, 17-22, 1986, San Francisco, USA

MEAN BEAM LENGTH FOR A SCATTERING MEDIUM

Get access (open in a dialog) DOI: 10.1615/IHTC8.4200
pages 769-772

Аннотация

The theory of mean beam length for the radiation of an isothermal volume, containing either absorbing molecules or absorbing particles, is extended to a scattering medium. Precisely, this medium itself does not scatter, but is filled with absorbing and scattering particles. Power leaving this isothermal and homogeneous volume, is derived assuming the uniformity and the isotropy of the flux of photons scattered once, the more accurate as the medium, is optically thin or as absorption dominates scattering. The mean beam length for this scattering medium, is defined, by analogy with the formartheory, as the radius of a hemisphere, radiating equally to the boundary, isothermal at the same temperature as the initial volume, replacing this volume, containing purely absorbing particles, with the same absorption coefficient as the initial medium. An expression of this mean beam length is given according to the preceding assumptions, as well as an asymptotic expansion for an optically thin medium. As optical thickness tends to zero, the mean beam length tends to the following value t four times the volume divided by the area, identical to the mean beam length of a purely absorbing medium : the former and the latter theories yield the same result.