細懸浮微粒(PM2.5)常吸附有毒物質隨呼吸系統進入人體，此將造成健康的危害。近年來臺灣常聽聞PM2.5達紫爆指標等級，因此探討PM2.5在氣管內的行為便是當今重要的議題之一。至於此方面研究，大致分為實驗操作、數值模擬、和理論分析。本文將使用數值模擬的方式，以商用軟體ANSYS FLUENT計算氣相空氣與固相粒子之三維不可壓縮暫態流。首先利用繪圖軟體CATIA建立健康及氣喘患者呼吸道模型，接著匯入ANSYS Meshing來產生網格。最後將網格導入FLUENT後，並利用正弦波模擬休息、輕微活動和適度運動吸氣時雷諾數(ReD)與時間的關係以計算流場。在入口處放入固態粒子，以使用者自訂函數(User Define Function，簡稱UDF)初始化固態粒子之初始條件後，求解雙向耦合之兩相暫態流，經計算結果發現：(1)在健康分歧管中，顆粒總質量沉積率極低；(2)在氣喘分歧管中，迪恩渦流及皺摺處二次流動將影響顆粒於管壁之沉積；(3)顆粒較大，則總沉積分率較高；(4)在相同條件下，三級氣喘管道的沉積質量皆大於二級氣喘管道。本文除了探討不同氣管模型和吸氣型態下粒子之沉積分率，亦對於沉積位置及分布的可視化著墨，以提供PM2.5健康風險評估或相關之研究資料。

Hazardous purple warning of PM2.5 often heard in Taiwan in the recent years. The gas velocity field and deposition fraction (DF) of the PM2.5 particles in the trachea and generations 10-11 and 10-12 of Weibel’s lung model are investigated. By using the ANSYS commercial code, comprehensive three-dimensional numerical model was introduced to study the gas-solid two-way flow behaviors in normal and asthmatic airways. The transient gas phase was modeled with laminar incompressible flow and the particle phase was treated by discrete phase model (DPM). In this work, the air flow rate of trachea is considered to be three activity levels, i.e., resting, light activity, moderate exercise, and the flow structure and PM2.5 particles deposition pattern for normal and asthmatic airway bifurcation are compared and discussed. The numerical results reveal that Dean effect is the important reason which causes particles deposition.

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