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.
