Fractal-like Aggregates: Relation between Morphology and Physical Properties

• Published in: Journal of colloid and interface science Vol. 229; no. 1; pp. 261 - 273
• Main Authors: Filippov, A.V., Zurita, M., Rosner, D.E.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.09.2000; Elsevier
• Subjects: Aerosols; aggregate numerical generation; Chemistry; Colloidal state and disperse state; energy and mass transfer; Exact sciences and technology; fractal dimension; General and physical chemistry; multipole expansion; Physical and chemical studies. Granulometry. Electrokinetic phenomena; quasi-Monte Carlo method; RDG theory; scaling laws; energy and mass transfer; fractal dimension; scaling laws; RDG theory; quasi-Monte Carlo method; multipole expansion; aggregate numerical generation; Geometrical structure; Scaling law; Monte Carlo method; Fractal dimension; Aerosols; Theoretical study; Property structure relationship; Spherical particle; Aggregate; Physical properties; Energy transfer; Mass transfer
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1006/jcis.2000.7027

A number of modern technological applications require a detailed calculation of the physical properties of aggregated aerosol particles. For example, in probing soot aerosols by the method called laser-induced incandescence (LII), the soot clusters are suddenly heated by a short, powerful laser pulse and then cool down to the temperature of the carrier gas. LII sizing is based on rigorous calculation of the soot aggregate heat-up and cooling and involves prediction of laser light absorption and energy and mass transfer between aggregated particles and the ambient gas. This paper describes results of numerical simulations of the mass or energy transfer between the gas and fractal-like aggregates of N spherical particles in either the free-molecular or continuum regime, as well as the light scattering properties of random fractal-like aggregates, based on Rayleigh–Debye–Gans (RDG) theory. The aggregate geometries are generated numerically using specially developed algorithms allowing “tuning” of the fractal dimension and prefactor values. Our results are presented in the form of easily applicable scaling laws, with special attention paid to relations between the aggregate gyration radius and the effective radius describing various transport processes between the aggregates and the carrier gas.