CFD Simulations of Respiratory Airflow in Human Upper Airways Response
to Walking and Running
Abstract
Walking and running are common types of physical activities people do in
day to day living, to improve health and physical fitness or for
recreation. During a physical activity, rate and depth of breathing
increase because working muscles need extra oxygen in order to produce
energy. In this study, computational fluid dynamics (CFD) simulations
were used to investigate respiratory airflow flow dynamics in human
upper airways response to walking and running. The numerical simulations
were done in a realistic CT-scan airway model using ANSYS Fluent 19.0
software. Flow fields were characterized numerical and flow patterns
were investigated in the airway model during inspiration and expiration
in response to walking and running. The axial velocity distribution and
secondary flow patterns were analyzed response to the two physical
activities at different cross-sections of the airway model. The maximum
velocity, wall pressure, and wall shear stress values for running were
respectively 3.2, 9.4 and 5.9 times higher than that of walking during
inspiration. More mixing of streamlines was observed during running than
walking because of the occurrence of greater turbulence. More skewed
flows at airway curvatures were observed at the inspiration than
expiration. The result of this study supported the fact that running is
a more intensive activity than walking from respiratory dynamics point
of view.