Deposition of Fractal-Like Aerosol Aggregates in a Model of Human Nasal Cavity

Abstract

Toxicity of diesel exhaust is related to the inhalation of nano-sized fractal-like aerosol aggregates. Their complex behavior (in comparison to spherical particles) should be taken into account in deposition modeling. The deposition of aerosol fractal-like aggregates in the model of a human nose was studied numerically for the flow rate corresponding to breathing conditions. The simplified geometry of the human nasal replica was implemented in the computational fluid dynamics (CFD) code (FLUENT) used for calculation of the three-dimensional airflow structure. A Brownian dynamic (BD) algorithm was applied for determination of the aggregates deposition in the nasal cavity during inhalation. These calculations were carried out for several populations of aggregates. The values of parameters used in the BD simulations for characterization of fractal-like aggregates, that is, fractal dimension (Df) and the radius of gyration (Rg), were in the range of 1.7-2.1 and 0.24-0.36 microm, respectively. These are the representative values for soot aggregates emitted from diesel engines. The results of computation show approximately 20% penetration of submicrometer aggregates through the nose and a weak dependence of deposition efficiency on Df and Rg values. The proposed methodology may lead to a more realistic description of deposition of nonspherical aerosol particles in the respiratory system. A more sophisticated approach for description of fractal-like aggregates dynamics is suggested for future studies.

Deposition of fractal-like soot aggregates in the human respiratory tract

“…Moskal, Makowski, Sosnowski, and Gradoń (2006) studied deposition of fractal-like aggregates of similar size to those studied here in the human nasal cavity, and reported a weak dependence of the deposition efficiency on D f . Previously, Yu and Xu (1987) studied DEP deposition in the lung for cluster aggregates that were modeled as porous spheres of equivalent mobility diameter and mass.…”

In-Vivo Measurements of Micrometer-Sized Particle Deposition in the Nasal Cavities of Taiwanese Adults

“…Numerous studies on the removal efficiency of inhaled particles in the nasal region have been performed in the past decades, by using either replicate casts or human volunteers (Hounam et al 1969;Lippman 1977;Stahlhofen et al 1989;Cheng et al 1991;Swift 1991;Zwartz and Guilmette 2001;Häußermann et al 2002;Moskal et al 2006;Storey-Bishoff et al 2008;Garcia et al 2009;Liu et al 2010). Many empirical equations were also developed to characterize the deposition efficiency in this region (Pattle 1961;Cheng 2003;Kelly et al 2004;Kim and Hu 2006).…”

Development of absolute intensity multi-angle light scattering for the determination of polydisperse soot aggregate properties

“…Its role in the environment is diverse; including direct heating of the atmosphere, triggering cloud formation, and inducing glacial melting [1,2]. Important information for health related simulations, as for example deposition modelling in the human body, include morphological and size parameters [3]. As a comprehensive diagnostic, the challenge is to determine simultaneously the overall soot concentration, the effective soot surface, primary particle diameter, as well as aggregate morphology, size, and corresponding distributions in real-time.…”