Numerical Investigation of inspiratory airflow in a realistic model of the human tracheobronchial airways

abstract

English

This study deals with the results of numerical simulations using computational fluid dynamics and a comparison with experiments performed with phase Doppler anemometry. The simulations and experiments were conducted in a realistic model of the human airways, which consist of the throat, trachea and tracheobronchial tree up to the fourth generation. An inspiratory part of breathing cycle was used with tidal volume of 0.5L, which correspond to a sedentary regime. The length of the inspiratory part of cycle was 2 s. As a boundary condition for the CFD simulations, experimentally obtained flow rate distribution in 10 terminal airways was used with zero pressure resistance at the throat inlet. Commercial CFD code (CD-Adapco’s (Siemens) StarCCM+) was used with an SST k-ω low-Reynolds Number RANS model. The total number of polyhedral control volumes was 2.6 million with a time step of 0.001 s. Comparisons were performed at several points in eight cross sections selected according to experiments in the trachea and the left and right bronchi. The results agree with experiments involving the oscillation (temporal relocation) of flow structures in the majority of the cross sections and individual local positions. Velocity field simulation in several cross sections shows a very unstable flow field, which originates in the tracheal laryngeal jet and propagates far downstream with the formation of separation zones in both left and right airways. The RANS simulation agrees with the experiments in almost all the cross sections and shows unstable local flow structures and a quantitatively acceptable solution for the time-averaged flow field.

Numerical simulation, Lungs, CFD, Airflow

ELCNER, J.; JÍCHA, M.; LÍZAL, F.; JEDELSKÝ, J.

21. 4. 2018

London, UK

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