Basic flow regimes in a human airway model measured by stereo scanning TR-PIV

Abstract The detailed analysis of the flow in the human lung is of high relevance for the optimization of mechanical ventilation. In this paper, the spatial and temporal development of the flow field in a realistic shaped model of the human lung is investigated for different pulsatile flow regimes. The model is based on the physiological data of a middle-aged and healthy male. The lung model consists of the tracheobronchial tree up to the 4 – 7th generation and is made from transparent silicone. The full optical access and the use of a refractive index matched test fluid offers the possibility to use Stereo-Scanning PIV to perform time-resolved three-dimensional measurements for all velocity components that cover the complete bronchial volume. The results of the analysis of the flow field will help to optimize ventilation strategies for artificial respiration. The investigated regions cover the trachea, the primary bronchi, and the right secondary bronchi, whereas all measurements are performed for a complete sinusoidal ventilation cycle. Three parameter combinations of the ventilation, composed of Reynolds and Womersley numbers, defined as viscous (Re = 10; α = 1.5), unsteady (Re = 40; α = 5), and convective (Re = 150; α = 1.5) were chosen with respect to the dominating fluid mechanical effects. The flow conditions are characterized by pressure measurements. In addition, steady measurements using a multi-plane PIV technique were analyzed for laminar (Re = 150) and turbulent (Re = 2650) flow for inspiration and expiration