A comparison between transport and diffusion calculations using a finite element-spherical harmonics radiation transport method
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Updated: Sep 29, 2026

The Diffusion of Passive Tracers in Laminar Shear Flow
Published on: May 1, 2018
E D Aydin1, C R E de Oliveira, A J H Goddard
1Canakkale Onsekiz Mart University, Faculty of Arts and Sciences, Department of Physics, Turkey. ed_aydin@hotmail.com
Abstract:
Most researchers choose the diffusion approximation to the transport equation as the model to describe photon migration in biological tissues. However, the applicability of this approximation is limited and, in certain cases, invalid. In this paper we introduce a two-dimensional, finite element-spherical harmonics (FE-P(N)) radiation transport method for the simulation of light propagation in tissue. The propagation of light is investigated first in a layered cylinder, which can be seen as a very simplistic approximation of a human head. Effects of the anisotropy factor g on the photon migration is then examined in homogeneous and heterogeneous media for different values of g and mu(s). The influence of void-like heterogeneities and channels in which absorption and scattering are very small compared with the surrounding medium on the transport of photons is also investigated. Significant differences between transport and diffusion calculations are shown to occur in all cases.
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