実形状肺気道内振動流の数値シミュレーション(流体工学,流体機械)  [in Japanese] Numerical Simulation of Oscillatory Flow in Realistic Model Human Airways(Fluids Engineering)  [in Japanese]

Computational fluid dynamics (CFD) simulation was carried out for an oscillatory flow in a 3-D realistic model of the human central airways, and the effect of airway geometry on the oscillatory flow structure was revealed. The computational model of multi-branching airways was prepared from X-ray CT images. Airway diameter ranges from approx. 2 to 14 mm. The flow in the airway model was simulated using CFD software: Fluent. The resultant flow showed differences compared with that observed in a simplified planar multi-branching model. The inspiratory flow patterns were relatively similar to the patterns observed in a simplified airway model, but the expiratory flow patterns strongly depended on the realistic airway geometry and showed more complicated secondary flow structures. Secondary flow velocities were higher in the realistic airway model than in the simplified airway model in both the inspiratory and expiratory flows. Performing Lagrangian fluid particle tracking, we discussed the convective dispersion due to asymmetric inspiratory and expiratory velocity profiles.