Particle deposition in replica healthy and emphysematous alveolar models using computational fluid dynamics.

摘要

Particle deposition in the pulmonary region of the lung has gained increasing interest in the past years. Of particular interest are nano-sized particles, because they have the potential of crossing the blood-gas barrier and into the capillaries. Many factors contribute to how and where particles deposit, such as lung morphology, breathing conditions, fluid flow characteristics, and alveolar wall movement. These many factors make simulating particle deposition in the alveoli difficult. The experimental in vivo studies have commonly used micron sized particles and there is a lack of data for smaller sized particles. Due to these many factors, deposition in the pulmonary region is not well understood. Furthermore, little attention has been paid to the emphysematous lungs, which have characteristics quite different than the healthy lung.;In this work, healthy and emphysematous replica acinus models were created from human lung casts using a 3D reconstruction software package. The models were used for simulating the particle deposition due to diffusion using Fine Particle Model (FPM). The FPM program was validated against an analytical solution using a straight tube, before moving on to predict the deposition in the alveolar models. Two particle sizes, 1 and 3 nm, were used to understand and compare pure diffusion in the lung using concentration contours. Results showed the particle deposition rate (particles/s) to be higher in the emphysemic. However, deposition rate per area (particles/m2s) was found to be higher in the healthy model. The deposition efficiency (% of particles that deposit) of the healthy model was greater than the emphysemic model, consistent with literature. Results were found to be lower than experimental in vivo measurements and whole lung model of local alveolar deposition (particles deposited in alveoli/particles entering alveoli) in comparison to our results in the pulmonary region, showing the importance of including axial diffusion effects. More work must be done experimentally and numerically before an understanding of deposition of particles of this size can be determined.