<p class="MsoNormal" style="text-align: justify; line-height: 150%">Information on the fiber particle transport and deposition in human nasal airways is of great importance in inhalation toxicology study. Due to the complex interactions between the inhaled aerosol particles and human respiratory airways, the particles' toxicity varies with their chemical composition, size, and shape. In the earlier computational study of fiber particle motion in human nasal cavities, overall deposition efficiency curves were evaluated and compared with the available experimental data. The majority of investigations were on micron-scale fiber particles, and the observed deposition fraction is strongly affected by fiber inertial impaction and the geometry of the cavity. However, the single-particle trajectory, very important information to perceive the airway particle flow interactions, is lacking. The benchmark of fiber characterization to its spherical equivalency is still not entirely performed. Limited existing evidence indicated that, when benchmarked by the impaction parameter, spherical particles tend to have a higher deposition fraction than that of the elongated fiber particles in the nasal cavity. More data is needed to elaborate on these observations and reveal the underlying physics. A more profound understanding of fiber transport in human airways may be obtained by comparing the fibrous particle deposition to that of the spherical particles.</p><p class="MsoNormal" style="text-align: justify; line-height: 150%">In this study, a simulation of transport and deposition of elongated particles in a realistic human nasal cavity model for a steady laminar airflow rate was developed. FLUENT 19.2 was used to solve the airflow conditions. The elongated ellipsoidal particle transport and deposition were simulated using the coupled translational and rotational equations of motion. The hydrodynamic drag and torque, shear-induced lift, and the gravitational force were included in the analysis. One-way coupling was assumed, and an in-house UDF (User Defined Function) code was developed and was implemented into the FLUENT-ANSYS code for analyzing the fiber transport and deposition. The flow field, the particle deposition efficiency curve, particle deposition pattern, and single-particle trajectories of fiber and sphere were analyzed and presented. The simulation results were compared with available experimental data and simulation results in the literature.</p>

Detailed Analysis of Fiber Motion in Human Nasal Airways

Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2021/volume/85284

ASME 2021 Fluids Engineering Division Summer Meeting (FEDSM2021)

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