Investigation of Ultrafine Particle Deposition in Human Airway to the 9^th Generation of Bronchial Tubes Using Computational Fluid and Particle Dynamics

¹ Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Fukuoka, Japan
² Faculty of Environment, University of Natural Resources and Environment, Ho Chi Minh, Vietnam

^* Corresponding author: ndkhoa@kyudai.jp

Abstract

The behavior of airborne particles in the human respiratory system is closely related to local tissue dosimetry and its associated health risks. The inhalation of these particles is known to be the origin of lung diseases, such as lung cancer, chronic obstructive pulmonary disease, and cardiovascular disease. To compensate for the difficulty of experiments involving volunteers, in silico studies using numerical models have been adopted as promising alternatives. Therefore, this study applied the computational fluid and particle dynamics technique to investigate the deposition of ultrafine particles in the human respiratory tract from the nostrils to the ninth generation of bronchi. A computational model was created using computed tomography images. The airflow patterns were simulated under steady and incompressible conditions at breathing flow rates of 7.5 and 15 L/min, respectively. The discrete phase was simulated for ultrafine particles with aerodynamic diameters of 2–100 nm. Consequently, the validation work confirmed the simulation accuracy for particle sizes > 25 nm. In the lower respiratory system, the total deposition fraction decreased as the particle size increased. In addition, the eighth generation is a focal point of the deposited particles, elucidated by the local deposition fraction. The results of this study will benefit further studies involving health risk assessments and drug delivery.