Electromagnetic scattering by an aggregate of spheres: far field

Xu, Yu-lin

doi:10.1364/ao.36.009496

Cited by 199 publications

(141 citation statements)

References 23 publications

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“…The other one is the generalized Mie-solution method (GMM). GMM was developed by Xu (1995Xu ( , 1997 based on the framework of the Mie theory for a single sphere and the addition theorems for spherical vector wave functions. It provides a rigorous and complete solution to nonoverlapping multisphere light scattering problems and can be readily applied to fractal soot aggregates ( Van-Hulle et al 2002;Liu and Snelling 2008).…”

Section: Generalized Mie-solution Methodsmentioning

confidence: 99%

“…Execution of this numerically exact method requires the positions, diameter, and refractive index of each constituent sphere (primary particle). Although CTM has become the most popular method to study the radiative properties of various scatterers , GMM has also been demonstrated to be a powerful tool to study radiative properties of various particles (Xu 1995(Xu , 1997Van-Hulle et al 2002;Liu and Snelling 2008). In fact, CTM and GMM share a very similar theoretical framework, though differences exist (Xu and Khlebtsov 2003).…”

Section: Generalized Mie-solution Methodsmentioning

confidence: 99%

“…The effect of prefactor on the absorption and scattering properties of fractal soot aggregates was studied by Liu et al (2009) using the generalized Mie-solution method (GMM) developed by Xu (1995Xu ( , 1997 and the RDG theory for fractal soot aggregates having identical fractal dimension of D f = 1.78 but two different prefactors of k f = 1.3 and 2.3. They generated fractal aggregates of prescribed fractal parameters using a tunable cluster-cluster algorithm described by Liu and Snelling (2008), which was based on the algorithms developed by Filippov et al (2000).…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Absorption and Scattering Properties of Soot Aggregates of Different Fractal Dimension at 532 nm Using RDG and GMM

Liu¹,

Wong

Snelling³

et al. 2013

Aerosol Science and Technology

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Radiative properties of numerically generated fractal soot aggregates of different fractal dimensions were studied using the numerically accurate generalized Mie-solution method (GMM) and the Rayleigh-Debye-Gans (RDG) approximate theory. Fractal aggregates of identical prefactor but different fractal dimensions, namely, 1.4, 1.78, and 2.1, were generated numerically using a tunable algorithm of cluster-cluster aggregation for aggregates containing up to 800 primary particles. Radiative properties of these aggregates were calculated at a wavelength of 532 nm assuming a soot refractive index of 1.6 + 0.6i. Four commonly used structure factors in the RDG approximation were used to investigate the effect of structure factor on the differential and total scattering cross-sections and the asymmetry factor. The differential and total scattering properties calculated using the RDG approximation become increasingly sensitive to the structure factor with increasing the fractal dimension. Primary particle interactions are the fundamental mechanism for the aggregate absorption enhancement for small aggregates and the shielding effect for larger aggregates. The extent of these two competing factors is dependent on the fractal dimension and aggregate size. RDG reasonably predicts the effect of fractal dimension on the scattering properties, but fails to account for the effect of aggregation or fractal morphology on the absorption property of fractal soot aggregates, though the error is in general less than 15%.

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Section: Generalized Mie-solution Methodsmentioning

confidence: 99%

Section: Generalized Mie-solution Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Investigation of Absorption and Scattering Properties of Soot Aggregates of Different Fractal Dimension at 532 nm Using RDG and GMM

Liu¹,

Wong

Snelling³

et al. 2013

Aerosol Science and Technology

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“…It has been successfully applied to compute the scattering properties of single core-mantle spheres (Hong et al 2008). Xu (1995Xu ( , 1996Xu ( , 1997 and Xu and Gustafson (2001) continued the development to produce what is known as the GMM method to deal with aggregates of arbitrary size and configuration, formed from monomers that are homogeneous spheres of possibly different radii and compositions. This GMM method was recently used to calculate the singlescattering properties of fractal aggregates by Van-Hulle et al (2002), Liu and Smallwood (2010, 2011), and Li et al (2010.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Water Coating on the Optical Scattering Properties of Fractal Soot Aggregates

Liu

Panetta

Yang

2012

Aerosol Science and Technology

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The effect of water coating of constituent monomers on the optical single-scattering properties of fractal soot aggregates is investigated numerically using core-mantle theory and approximations involving two effective medium theories. A cluster-cluster aggregation algorithm is used to numerically generate fractal aggregates, and the core-mantle Generalized Multi-particle Mie (GMM) method is used to compute the exact single-scattering properties of soot aggregates with water-coated monomers. Comparisons are then made with results obtained using approximations that combine either the GMM method or the Rayleigh-Debye-Gans (RDG) method with either the Maxwell-Garnett or the Bruggeman effective medium approximation (a total of four approximation methods). The optical properties calculated are the extinction and absorption cross sections, the single-scattering albedo, and the phase matrix of water-coated fractal aggregates; these calculations are done for two wavelengths, 0.628 µm and 1.1 µm. Water coating of the fractal aggregates is shown to increase the extinction and absorption cross sections, the single-scattering albedo, and forward scattering, but decrease backward scattering. The combination GMM + Maxwell-Garnett gives approximations that are quite good over a range of coating thicknesses and aggregate size. The combination GMM + Bruggeman performs less well, overestimating the extinction and absorption cross sections and underestimating the single-scattering albedo. In the case of RDG, the better combination is with the Bruggeman approximation, but the errors involved are greater than with the GMM + MaxwellGarnett combination. Results from simple idealized calculations indicate that the differences between results with the MaxwellGarnett and Bruggeman approximations should be even larger in cases of aerosol cores that are less absorptive than soot.

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“…Figure 2. We used the rigorous solution for scattering by an aggregate of spheres [Xu, 1995[Xu, , 1997] that has been thoroughly tested at the University of Florida microwave scattering facility and shown to be accurate [Xu and Gustafson, 1997;1999 As stated in KMGG, the search area of the Fence was divided into two regions, 1000-3000 km altitude and 3000-20,000 km altitude, in order to accommodate different published values for the altitude of cometary breakup. For the high altitude range, after allowing for the vast increase in search area above 3000 km and the change in sensitivity of the Fence with range, KMGG found the small comet detection rate to be comparable for both altitude regimes.…”

Section: Introductionmentioning

confidence: 99%

Reply [to “Comment on “A search for small comets with the Naval Space Command Radar” by S. Knowles et al.”]

Knowles¹,

Meier²,

Gustafson³

et al. 1999

J. Geophys. Res.

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Electromagnetic scattering by an aggregate of spheres: far field

Cited by 199 publications

References 23 publications

Investigation of Absorption and Scattering Properties of Soot Aggregates of Different Fractal Dimension at 532 nm Using RDG and GMM

Investigation of Absorption and Scattering Properties of Soot Aggregates of Different Fractal Dimension at 532 nm Using RDG and GMM

The Influence of Water Coating on the Optical Scattering Properties of Fractal Soot Aggregates

Reply [to “Comment on “A search for small comets with the Naval Space Command Radar” by S. Knowles et al.”]

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