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An experimental study of respiratory aerosol transport in phantom lung bronchioles
The transport and deposition of micrometer-sized particles in the lung is the primary mechanism for the spread of aerosol borne diseases such as corona virus disease-19 (COVID-19). Considering the current situation, modeling the transport and deposition of drops in human lung bronchioles is of utmos...
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Published in: | Physics of fluids (1994) 2020-11, Vol.32 (11), p.111903-111903 |
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Main Authors: | , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The transport and deposition of micrometer-sized particles in the lung is the primary
mechanism for the spread of aerosol borne diseases such as corona virus disease-19
(COVID-19). Considering the current situation, modeling the transport and deposition of
drops in human lung bronchioles is of utmost importance to determine their consequences on
human health. The current study reports experimental observations on deposition in
micro-capillaries, representing distal lung bronchioles, over a wide range of
Re that imitates the particle dynamics in the entire lung. The
experiment investigated deposition in tubes of diameter ranging from 0.3 mm to 2 mm and
over a wide range of Reynolds number (10−2 ⩽ Re ⩽
103). The range of the tube diameter and Re used in this
study is motivated by the dimensions of lung airways and typical breathing flow rates. The
aerosol fluid was loaded with boron doped carbon quantum dots as fluorophores. An aerosol
plume was generated from this mixture fluid using an ultrasonic nebulizer, producing
droplets with 6.5 µm as a mean diameter and over a narrow distribution of
sizes. The amount of aerosol deposited on the tube walls was measured using a
spectrofluorometer. The experimental results show that dimensionless deposition
(δ) varies inversely with the bronchiole aspect ratio
(
L
¯
), with the effect of the Reynolds number
(Re) being significant only at low
L
¯
. δ also increased with increasing
dimensionless bronchiole diameter (
D
¯
), but it is invariant with the particle size based Reynolds
number. We show that
δ
L
¯
∼
R
e
−
2
for 10−2 ⩽ Re ⩽ 1, which is
typical of a diffusion dominated regime. For Re ⩾ 1, in the impaction
dominated regime,
δ
L
¯
is shown to be independent of Re. We also
show a crossover regime where sedimentation becomes important. The experimental results
conclude that lower breathing frequency and higher breath hold time could significantly
increase the chances of getting infected with COVID-19 in crowded places. |
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ISSN: | 1070-6631 1089-7666 |
DOI: | 10.1063/5.0029899 |