Research On The Characteristics Of Airflow And Deposition Of The Particulate Matter In The Real Upper Respiratory Tracts Based On Healthy Adult CT Images

With the haze weather occurs frequently in domestic cities, poisonous particulatematters in air do great harm to human’s health, and the prevalence of respiratorydiseases also increase significantly. Fine particulate matter (PM2.5, refers to theambient air aerodynamic diameter less than or equal to2.5micron particles can enterthe human alveolar) greater harm to human body. On the other hand, in medicaltechnology, because the drug aerosol is useful in the treatment of human respiratoryless side effects and quickly so widely used in medical treatment.In this paper, a real human respiratory tracts model based on199CT images ofupper respiratory tract of healthy adult men was established. Three-dimensionalreconstruction of upper respiratory tracts, including nasal cavity, pharynx, larynx, apart of trachea true master were reconstructed by using the medicine3D softwareMimics. This model was meshed by ICEM CFD. The flow characteristics within theupper respiratory tracts during30L/min (normal breathing), and90L/min (vigorousexercise) were investigated in the steady breathing mode. Meanwhile, the circularbreathing characteristic were also been discussed. The DPM model was applied todiscuss the particle of density1000kg/m3deposition, with a diameter1μm,2.5μm,5μm,10μm respectively. The same diameter particle deposition rates under differentbreathing rates (30L/min,60L/min,90L/min) were also simulated.The results show that changes in the flow field within the real human respiratorytract are not significantly notable under the mode of steady and circular breathing.When the airflow passes through the nose, turbulence phenomenon appears. Because pharyngeal exists jet phenomenon, speed direction changes in the throat, and speedincreases slightly. When the airflow passes through the pharynx, larynx, the vortexappears. On the other hand, there is a delay of flow field under mode of circularbreathing, With the particle size increasing, the whole particle deposition rates in theupper respiratory tract of humans increase significantly. The particle with largerdiameter are mainly deposited in the nasal cavity more easily. In general, particles withdifferent size deposition rates in the respiratory tract typical position are different.The deposition rates in pharynx and larynx are larger, and followed by the nasal cavity,primary tracheal in succession. The deposition rates of particulate matter in the upperrespiratory tracts increase slightly with the increase of respiration rate. The increase ofthe particle size has greater influence on deposition rate, compared to respiration rates.The study can be sucked deep understanding of fine particulate matter depositedin the body rule the road, and to grasp the intensity of respiratory aerosol delivery ofdrugs within the human body and the effective utilization of a reference value.