Validated numerical simulation of airflow in child respiratory airways

Abstract

Both pulmonary airway geometry and breathing pattern evolve from birth to adulthood. These gradual changes significantly influence airflow dynamics and subsequently particle transport and deposition. Regarding the airway structure, the differences between infants and adults are most profound till 5 years of age. Since that age the child airway geometry can be downsized from adult lungs. The objective of the present work was to investigate airflow patterns in child airways. The digital model of male respiratory airways was downsized to dimensionally correspond to a 5–year old child. Airflow simulations with properly validated RANS k–ω turbulence model were performed under steady inhalation boundary conditions. The inspiratory flow rate was 12.5 L/min. The velocity profiles just upstream of the first bifurcation were validated by Laser–Doppler anemometry (LDA) experiments. A replica of the same geometry as the one used in the simulation was 3D printed and part of the trachea was replaced by a glass tube. LDA measurements in several points upstream of the first bifurcation were carried out. The validated flow patterns were compared to the ones obtained in adult lungs.