Best Practice Advice AC7-01: Difference between revisions
| Line 8: | Line 8: | ||
=Best Practice Advice= | =Best Practice Advice= | ||
==Key Fluid Physics and Deposition Mechanisms== | ==Key Fluid Physics and Deposition Mechanisms== | ||
Airflow in the human upper airways transitions to turbulence due to geometric effects, | |||
such as the bent in the oropharyngeal region and the constriction at the glottis. The bent | |||
in the oropharynx causes substantial filtering of inhaled aerosols due to inertial impaction | |||
on the airway walls. Filtering in the extrathoracic airways increases as the particle size | |||
and inhalation flowrate increase. | |||
As we move in the tracheobronchial airways, the Reynolds number is reduced because | |||
the air travels through a larger total cross-sectional area. As a result, airflow relaminarizes | |||
in the first generations. At the flowrate examined in the present AC, the main deposition | |||
mechanism in this region is inertial impaction, with significant deposition at the bents and | |||
the bifurcations. At lower flowrates, deposition can also be influenced by gravitational | |||
sedimentation because the residence times of the particles in the bronchial airways is | |||
longer. | |||
<br/> | <br/> | ||
---- | ---- | ||
Revision as of 12:46, 2 October 2019
Aerosol deposition in the human upper airways
Application Challenge AC7-01 © copyright ERCOFTAC 2019
Best Practice Advice
Key Fluid Physics and Deposition Mechanisms
Airflow in the human upper airways transitions to turbulence due to geometric effects, such as the bent in the oropharyngeal region and the constriction at the glottis. The bent in the oropharynx causes substantial filtering of inhaled aerosols due to inertial impaction on the airway walls. Filtering in the extrathoracic airways increases as the particle size and inhalation flowrate increase.
As we move in the tracheobronchial airways, the Reynolds number is reduced because
the air travels through a larger total cross-sectional area. As a result, airflow relaminarizes
in the first generations. At the flowrate examined in the present AC, the main deposition
mechanism in this region is inertial impaction, with significant deposition at the bents and
the bifurcations. At lower flowrates, deposition can also be influenced by gravitational
sedimentation because the residence times of the particles in the bronchial airways is
longer.
Contributed by: *** — ***