Abstract
To reveal the nature of turbulence in a lung, the measurements of turbulence in the oscillatory flow in realistic model human central airways were made by particle image velocimetry (PIV). The transparent silicon model of multi-branching airways was fabricated from X-ray CT images by rapid prototyping. The multi-branching airways comprise trachea, right and left bronchi and airway diameters range from 14 to 2 mm. Experiments were performed for the Reynolds number from 1200 to 2200 and for the Womersley number from 1.9 to 2.3 in the trachea. The spatial and temporal variations of turbulent intensity were strongly dependent on the airway geometry and the phase of oscillatory flow. The expiratory flow generates strong turbulence which explosively occurs in the entire cross section especially in the right bronchi, whereas the inspiratory flow generates relatively weak turbulence near the airway wall.
