11 November 1991 Discrete-angle radiative transfer in a multifractal medium
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Proceedings Volume 1558, Wave Propagation and Scattering in Varied Media II; (1991); doi: 10.1117/12.49612
Event: San Diego, '91, 1991, San Diego, CA, United States
Abstract
A simplified (discrete angle, DA) radiative transfer theory is presented as a computationally and conceptually advantageous alternative to standard (continuous angle) theory. After briefly reviewing the basic ideas of random fractal geometry and multifractal cascade theory, we present some of our recent two-dimensional DA numerical simulations of transfer through a specific log-normal multifractal cloud model where the radiation fields are spatially resolved on a 1024 x 1024 point grid. Using this data base, we demonstrate (1) how in inhomogeneous transfer problems horizontal fluxes work in quite subtle ways to create dramatic overall differences with homogeneous predictions for the same amount of scattering material, and (2) how strongly multiple scattering can smooth extremely singular density fields. Furthermore, both of these effects are enhanced by increasing optical thickness which can be viewed as a measure of the strength of the nonlinear coupling between the density and radiance fields. Finally, we discuss some basic inequalities that arise between the various ways of computing overall (spatially averaged) response to illumination.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Anthony B. Davis, Shaun Lovejoy, Daniel Schertzer, "Discrete-angle radiative transfer in a multifractal medium", Proc. SPIE 1558, Wave Propagation and Scattering in Varied Media II, (11 November 1991); doi: 10.1117/12.49612; https://doi.org/10.1117/12.49612
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KEYWORDS
Clouds

Scattering

Wave propagation

Photons

Diffusion

Fractal analysis

Radiative transfer

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