CFD Evaluation of the Influence of Physical Mechanisms, Particle Size, and Breathing Condition on the Deposition of Particulates in a Triple Bifurcation Airway

Particle deposition in the human lungs is mainly influenced by the fluid dynamics and the particle properties, such as the size and the deposition mechanisms. A three-dimensional gas particle flow model to predict particle deposition and flow patterns in four generations of the human lung, located in the bronchial region, is presented in this paper. Four breathing conditions (sleep, resting, moderate activity, and intense activity) were simulated, using the commercial code ANSYS Fluent (R) version 14.5. The particle diameter was varied from 1 to 10 mu m. The results showed that deposition in each of the three bifurcations was not uniform and should be analyzed separately based on particle diameter. The influence of gravitational settling and Brownian diffusion on particle deposition was also investigated and quantified. The greater difference in the deposition between cases considering these physical mechanisms and not considering it occurred in situations involving lower velocity, showing a value of 172 % for gravitational settling mechanism and a difference of 11 % for Brownian diffusion. Furthermore, it was observed that the total deposition increased with the Reynolds and Stokes numbers, suggesting that exercise practices should be avoided in situations with high levels of suspended particulate matter.