An experimental platform to investigate the propagation of turbulent fluctuations in a lung model

Abstract Understanding airflow dynamics and aerosol deposition in lung airways is crucial for advancing respiratory therapies. However, the complex hierarchical structure of the lung, characterised by up to 23 generations of asymmetrically branching airways, poses significant challenges for both numerical simulations and experimental investigations, particularly in capturing turbulent fluctuations deep within the respiratory tract. In this study, we introduce an experimental platform designed to investigate the propagation of turbulent fluctuations in a simplified lung model. Our approach employs a 3D-printed, rigid, planar airway geometry that represents generations 5 to 7. Hot-wire anemometry, with three probes strategically placed along the centerlines of the branches, is used to measure the flow regimes and fluctuation characteristics simultaneously at multiple locations, under various inlet conditions. Preliminary results indicate that, for a quasi-laminar inlet flow ( Re ≈ 1200), turbulence is generated after the first bifurcation ( G 5 ), while a fully turbulent inlet flow (due to a 90° sharp inlet bend and Re ≈ 1200) induces an observable energy decay through subsequent generations ( G 6 , G 7 ). These findings provide complementary insights to CFD analyses, underscoring the need for further investigation into the mechanisms of turbulent propagation in the lung.