Anisotropic media scattering

For an isotropic medium such as a collection of many randomly oriented particles, which may themselves be anisotropic, the scattered irradiance and hence the differential scattering cross section is independent of . 

The ability of anisotropic and anisometric particles to assume some co-orientation in external force fields is not only responsible for significant changes in scattering properties but also causes birefringence (double refraction), i.e., the average refractive indexes of two beams polarized in perpendicular planes happen to be different. The specific orientation of particles and birefringecne may be caused by the action of electric field (Kerr effect), magnetic field (Cotton-Mouton effect), or in the case of anisotropic particles by flow of medium (Maxwell effect) [25]. 

Isotropic scattering indicates that the radiant energy incident on a volume element is uniformly distributed to all directions. For an isotropically scattering medium, all a, coefficients of the phase function are zero, except a0. If only a0 and the first coefficient a, are considered, then one obtains the linearly anisotropic phase function, which means that the phase function is a linear function of cos 0 (or, in the case of an azimuthally symmetric medium, a linear function of p = cos 9). 

It is important to ask the following questions before a specific model is chosen. (1) Is the medium geometry simple (2) Are there steep temperature and species concentration distributions in the medium (3) Are there anisotropically scattering particles (4) If there are, what kind of scattering phase function approximations can be used for them Having some approximate answers to these questions will help to expedite the selection process. 

H. Lee, and R. O. Buckius, Scaling Anisotropic Scattering in Radiation Heat Transfer for a Planar Medium, ASME J. Heat Transfer, (104) 68-75,1982. 

Perrin (1942) has shown that this relation holds for scattering from any medium which is macroscopically isotropic — although the individual particles of which it is composed may be anisotropic — and which does not show optical rotation x. 

Depolarized dynamic light scattering is based on the analysis of time fluctuations in the scattered light intensity due to Brownian motion of optically anisotropic particles suspended in a liquid medium. ... 

Nematic solutions present an anisotropic scatterii medium, with fluctuations in molecular orientation resulting in appreciable depolarized scatterii Thus, in this case, it is the horizontally polarized component the scattering with vertically polarized incident light that is of most interest [134, 135]. The scattering from concentration fluctuations is much smaller than that from orientation fluctuations. The anisotropy of a nematic mesophase of rodlike chains is measured by an order parameter S, given by [119,134, 135]... 

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