Numerical Investigation On The Transport And Deposition Of Particulate Matter In Human Pulmonary Airways

Particle deposition in respiratory tract could increase human oxidative stress and then may cause airway inflammation et al, Recently, epidemiology researches find out increasing concentration of inhalable particulate matter led to the rise of morbidity and mortality in respiratory diseases, cardiovascular diseases. Therefore, the research of particle deposition in the human lung is essential to the health risk assessment of particulate pollutants. On the other side, inhaling medicines therapy, which means delivering drugs to the body through the lungs, is recognized as a versatile, highly promising and until recently little exploited route for drug delivery worldwide, the study of inhaling drug deposition in the respiratory tract provides an important reference value to improve the efficacy of inhalation therapy.Based on respiratory physiology and human lung structure, the respiratory and airway parameters were applied to the research, physical model of health and obstruction bronchial from the 3rd generation to 6th generation were established. Euler-Lagrange method was selected to simulate the air flow and particulate matter trajectory, N-S equation and Newton's second law were taken as the control equations; Through numerical simulation, the airflow and particle deposition were analyzed, the targeting drug delivery in the obstruction airway were optimized, the airflow field distribution and the particle deposition results were taken to show the characteristic of airflow and particle movement in human airways system. Particles deposition rate and region are the critical parameters for the assessment of particles effects on human health, the airflow field and particle physical properties are the main factors that affect the deposition conditions, first, by changing the airflow Reynolds number at model entrance, deposition of particulate matter in the human airways at different respiration rate were obtained; second, particle diameter and density were the key factors to the deposition, results in characteristics of particulate matter with different properties of deposition in the human airways were studied; third, adjusting the relative orientation of gravity and the physical model, the gravity on the particles deposition and regulation of drug targeting is achieved.The numerical methods were validated by comparing the simulation results with experimental results. Research shows that the total deposition concentration of particles lager than 2.5μm in diameter increases with entrance Reynolds number, the inlet velocity distribution significantly affected the airflow field and particle deposition. For the particles diameter between 0.1-10μm, the smaller the particle size, the total deposition is lower in the model; the gravity effect on particle deposition is more significant under low Reynolds number conditions. Particulate pollutants in the obstructed bronchial may lead to further deterioration of obstructive symptoms, 10μm particles in the inlet air Reynolds number for the 2000 target coefficient is the maximal value, particle density and the direction of gravity on the deposition of the targeting effects. Through this research, a theoretical basis for further understanding of particles and the relationship between human health and the drug delivery mechanism was provided.