Některé aspekty pohybu částic při cyklickém proudění v realistickém modelu dýchacího traktu člověka

SOME ASPECTS OF PARTICLE MOTION UNDER CYCLIC FLOW IN REALISTIC HUMAN AIRWAY MODEL

článek ve sborníku ve WoS nebo Scopus

en

Deeper understanding of aerosol transport in human lungs is needed to increase transport efficiency of therapeutic drugs. We investigate a motion of micron-size liquid-aerosol particles in a transparent thin-wall realistic airway model using Phase Doppler Particle Anemometry (P/DPA). A pneumatic mechanism is used to generate cyclic flow of a dilute particle-laden air simulating three distinct sinusoidal breathing patterns. Velocity measurement of monodisperse aerosol particles of di-2-ethylhexyl sabacate (DEHS) is performed in several cross-sections of the airway model in trachea and the first three generations of bronchi. Influence of airway geometry and breathing regimes on the flow field in the airway model is discussed. Mean and fluctuating components of axial velocity during the breathing cycle are evaluated and used for calculation of time resolved axial turbulence intensity in measurement points. Exemplary plots of the mean axial velocity and turbulence intensity are documented in the paper. Varying level of the turbulence intensity during breathing cycle indicates a transition between laminar and turbulent flow character. The turbulence intensity is also found to differ significantly from point to point and also to differ between inspiration and expiration phases at given point. The results of P/DPA measurement show some specific deformations of the shape of the mean sinusoidal-like velocity profile. Velocity jumps near zero-velocity crossings and deformations of the time slope of the particle velocity are detected and related to flow dynamics in the branching-tube model. Vortices and flow separation generated in the complex realistic model are found to be responsible for these effects.

Rostoucí zájem o pochopení transportu aerosolu v lidských plicích souvisí s podáváním inhalovaných farmaceutik. Průhledný realistický model dýchacích cest člověka s nesymetrickým větvením a prostorovou geometrií obsahující části od hrdla až třetí-čtvrté generace bronchů byl použit pro studium transportu kapalných aerosolových částic s pomocí fázové dopplerovské anemometrie. Rychlost částic o velikosti v rozsahu 1 do 8 mikronů byla měřena při ustálených a cyklických podmínkách proudění pomocí fázového Dopplerovského analyzátoru. Byly vyhodnoceny údaje o časově středované a fluktuační složce rychlosti a následně o intenzitě turbulence. Vybrané záznamy průběhu rychlosti částic a intenzity turbulence ukazují na složitost proudění s přechody z laminárního do turbulentního a s přítomností lokálních vírů. a separací proudění.

Deeper understanding of aerosol transport in human lungs is needed to increase transport efficiency of therapeutic drugs. We investigate a motion of micron-size liquid-aerosol particles in a transparent thin-wall realistic airway model using Phase Doppler Particle Anemometry (P/DPA). A pneumatic mechanism is used to generate cyclic flow of a dilute particle-laden air simulating three distinct sinusoidal breathing patterns. Velocity measurement of monodisperse aerosol particles of di-2-ethylhexyl sabacate (DEHS) is performed in several cross-sections of the airway model in trachea and the first three generations of bronchi. Influence of airway geometry and breathing regimes on the flow field in the airway model is discussed. Mean and fluctuating components of axial velocity during the breathing cycle are evaluated and used for calculation of time resolved axial turbulence intensity in measurement points. Exemplary plots of the mean axial velocity and turbulence intensity are documented in the paper. Varying level of the turbulence intensity during breathing cycle indicates a transition between laminar and turbulent flow character. The turbulence intensity is also found to differ significantly from point to point and also to differ between inspiration and expiration phases at given point. The results of P/DPA measurement show some specific deformations of the shape of the mean sinusoidal-like velocity profile. Velocity jumps near zero-velocity crossings and deformations of the time slope of the particle velocity are detected and related to flow dynamics in the branching-tube model. Vortices and flow separation generated in the complex realistic model are found to be responsible for these effects.

transport aerosolu, realistický model, dýchací cesty člověka, cyklické proudění, Dopplerovská anemometrie

Particle Motion, Realistic Human Airway Model, Cyclic Flows, Phase Doppler Anemometry

2010

02.11.2010

National Kaoshiung University of Applied Sciencies

Taiwan

978-986-6184-25-3

Proceedings of the 21st International Symposium on Transport Phenomena, Kaohsiung, Taiwan

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1–8

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