TY - JOUR

T1 - A simple model for gravitational deposition of non-diffusing particles in oscillatory laminar pipe flow and its application to small airways

AU - Kojic, M.

AU - Tsuda, A.

PY - 2004/2

Y1 - 2004/2

N2 - Gravitational deposition of non-diffusing particles from oscillatory laminar flows in a horizontal pipe is studied. Developing a simple mathematical model, we demonstrate that when the time for gravitational sedimentation (T d) becomes appreciable relative to the time for flow oscillation (T), the gravitational deposition may no longer be approximated by the classical solution based on steady flow (J. Aerosol Sci. 3 (1972) 351). The analysis shows that an error caused by this approximation increases with the ratio of Td/T (for instance, the errors in the estimation of deposition site are 1.5%, 5.9%, and 128% for Td/T=0.05, 0.1, and 0.5, respectively); the application of the commonly used steady flow-based solutions to dominantly oscillatory flows, such as tidal breathing in lung airways, may therefore significantly underestimate local deposition density. We conclude that the oscillatory nature of tidal airflow must be taken into account when one calculates gravitational deposition of micrometer size particles in small airways of the human lung.

AB - Gravitational deposition of non-diffusing particles from oscillatory laminar flows in a horizontal pipe is studied. Developing a simple mathematical model, we demonstrate that when the time for gravitational sedimentation (T d) becomes appreciable relative to the time for flow oscillation (T), the gravitational deposition may no longer be approximated by the classical solution based on steady flow (J. Aerosol Sci. 3 (1972) 351). The analysis shows that an error caused by this approximation increases with the ratio of Td/T (for instance, the errors in the estimation of deposition site are 1.5%, 5.9%, and 128% for Td/T=0.05, 0.1, and 0.5, respectively); the application of the commonly used steady flow-based solutions to dominantly oscillatory flows, such as tidal breathing in lung airways, may therefore significantly underestimate local deposition density. We conclude that the oscillatory nature of tidal airflow must be taken into account when one calculates gravitational deposition of micrometer size particles in small airways of the human lung.

KW - Aerosols

KW - Deposition

KW - Lung

KW - Sedimentation

KW - Settling

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U2 - 10.1016/j.jaerosci.2003.08.005

DO - 10.1016/j.jaerosci.2003.08.005

M3 - Article

AN - SCOPUS:1642533522

VL - 35

SP - 245

EP - 261

JO - Journal of Aerosol Science

JF - Journal of Aerosol Science

SN - 0021-8502

IS - 2

ER -