Study On The Characteristics Of Transporation And Deposition Of Inhalational Particles In Respiratory Tract

The serious influence of atmospheric pollution to human body health has already aroused worldwide attention, and aerosol is the main reason of atmospheric pollution. Among all kinds of aerosol, inhalational particle is the one which can be inhaled into lower respiratory tract and is related to respiratory system disease according to epidemiology research. Therefore, it is with great necessity to study flow field of human upper respiratory tract and deposition characteristic of inhalational particle.Based on the present reseach, a new entire 3-dimensional geometry from mouth, pharynx, larynx, trachea to triple bifurcation was proposed in this study. Commercial software CFD was utilized to solve primary flow under steady respiration which include three breathing intensity (Q = 30 L/min,Q = 60 L/min and Q = 90 L/min) and primary flow under unsteady respiration at different time. In succession, particles were traced in the Lagrangian frame, and at the same time, particle deposition fraction and position were recorded. The deposition fraction of inhalational particles obtained from numerical simulation show relatively good agreement when compared with the experimental data in the literature.Standard k ?ωand RNG k ?εturbulence model were used in the numerical simulation to solve the flow field in the upper respiratory tract. By analyzing the characteristic of flow field, a conclusion can be drew that the maximum velocity appears at larynx during breathing; a spray structure appears respectively at pharynx and larynx because of their cross-sectional reduction of the tract; the higher flow velocity in bronchia bifurcation appears in the direction of approaching central axis of the upper bifurcation. Based on the study above, the characteristic of transportation and deposition of inhalational particles and its influencing factors have been simulated and analyzed. The result shows that breathing intensity, particle diameter and particle density are the three key factors influencing the deposition of inhalational particles. The conclusion of this paper can be a foundation for therapeusis and study on inhalational particles health effects.