Polydisperse Aerosol Transport and Deposition in Upper Airways of Age-Specific Lung

Abstract

A comprehensive understanding of airflow characteristics and particle transport in the human lung can be useful in modelling to inform clinical diagnosis, treatment, and management, including prescription medication and risk assessment for rehabilitation. One of the difficulties in clinical treatment of lung disorders lies in the patients’ variable physical lung characteristics caused by age, amongst other factors, such as different lung sizes. A precise understanding of the comparison between different age groups with various flow rates is missing in the literature, and this study aims to analyse the airflow and aerosol transport within the age-specific lung. ANSYS Fluent solver and the large-eddy simulation (LES) model were employed for the numerical simulation. The numerical model was validated with the available literature and the computational results showed airway size-reduction significantly affected airflow and particle transport in the upper airways. This study reports higher deposition at the mouth-throat region for larger diameter particles. The overall deposition efficiency (DE) increased with airway size reduction and flow rate. Lung aging effected the pressure distribution and a higher pressure drop was reported for the aged lung as compared to the younger lung. These findings could inform medical management through individualised simulation of drug-aerosol delivery processes for the patient-specific lung.

Heat Wave and Bushfire Meteorology in New South Wales, Australia: Air Quality and Health Impacts

“…In addition, the conditions of stationary walls and no-slip are applied to the airway walls. A ‘trap’ boundary condition is also used as a Discrete Phase Model (DPM) wall condition [ 46 , 47 ]. As a result of the trap conditions, particles should be deposited when the particle touches the lung wall.…”

How severe acute respiratory syndrome coronavirus-2 aerosol propagates through the age-specific upper airways

“…Studies to date mostly used uniform inlet conditions for one-way inhalation ( Islam et al , 2021a ; Kuprat, 2021 ; Zhao et al , 2021 ) and parabolic ( Bass et al , 2021 ; Chen et al , 2021 ; Fan et al , 2021 ; Hayati et al , 2021 ). During inhalation, the uniform flow field could become highly turbulent at the mouth–throat area at a flow rate of >30 lpm ( Islam et al , 2018 ; Islam et al , 2019 ; Kleinstreuer and Zhang, 2003 ; Zhang et al , 2005 ), and the flow profile becomes parabolic at the trachea and upper airways ( Gemci et al , 2008 ; Islam et al , 2017 ). This study used uniform inlet conditions at the mouth–throat inlet.…”

“…This study did not consider all the bifurcations; only the first five bifurcations were considered in the analysis. Therefore, the open outlet condition used at the outlet is adopted from the published literature ( Cui et al , 2021 ; Islam et al , 2021a ).…”

Aerosol Particle Transport and Deposition in Upper and Lower Airways of Infant, Child and Adult Human Lungs

“…The velocity inlet and pressure outlet boundary conditions are considered at the lung model's inlet and outlet, respectively [29][30][31][32][33]. The airway wall was considered to be stationary, and a non-slip boundary condition is used on the wall surface [34][35][36]. The inhaled air flow rate is considered evenly distributed among all the 2 n bifurcations of generation G-n. As a result, the inlet air flow rate of each inlet of G-n is Q n e = Q in /2 n , where Q in is the inlet flow rate at G0.…”