Modeling of the transport, hygroscopic growth, and deposition of multi-component droplets in a simplified airway with realistic thermal boundary conditions

Abstract

Accurate predictions of the droplet transport, evolution, and deposition in human airways are critical for the quantitative analysis of the health risks due to the exposure to the airborne pollutant or virus transmission. The droplet/particle-vapor interaction, i.e., the evaporation or condensation of the multi-component droplet/particle, is one of the key mechanisms that need to be precisely modeled. Using a validated computational model, the transport, evaporation, hygroscopic growth, and deposition of multi-component droplets were simulated in a simplified airway geometry. A mucus-tissue layer is explicitly modeled in the airway geometry to describe mucus evaporation and heat transfer. Pulmonary flow and aerosol dynamics patterns associated with different inhalation flow rates are visualized and compared. Investigated variables include temperature distributions, relative humidity (RH) distributions, deposition efficiencies, droplet/particle distributions, and droplet growth ratio distributions. Numerical results indicate that the droplet/particle-vapor interaction and the heat and mass transfer of the mucus-tissue layer must be considered in the computational lung aerosol dynamics study, since they can significantly influence the precise predictions of the aerosol transport and deposition. Furthermore, the modeling framework in this study is ready to be expanded to predict transport dynamics of cough/sneeze droplets starting from their generation and transmission in the indoor environment to the deposition in the human respiratory system.

Change of Composition, Source Contribution, and Oxidative Effects of Environmental PM2.5 in the Respiratory Tract

“…The geometric size is illustrated in previous studies. [19][20][21] proposed an empirical correlation for particle deposition in the MT region based on previous human experimental results. 22 Later, Zhang developed the MT model used in this study and evaluated its performance of mimicking particle deposition.…”

From Static to Dynamic: A Review on the Role of Mucus Heterogeneity in Particle and Microbial Transport

“…Besides models for simulation, Chen et al 249 reported a prediction model of hygroscopic droplet deposition in airways using parameters such as temperature distribution, relative humidity distribution, deposition efficiencies, droplet or particle distribution, and droplet growth ration distributions (Figure 4c). It is found that high inhalation flow rate can decrease the mucus temperature and airway relative humidity and cause the growth of hydroscopic droplets.…”

“…(c) Illustration of diameters and locations for the deposited droplets and escaped droplets and particles when the flow rate is 15 L/min with the same initial Stk = 0.036. Panel (c) reproduced with permission from ref . Copyright 2021 Elsevier.…”

Research on Water Droplet Movement Characteristics in the Last Two Stages of Low-Pressure Cylinder of Steam Turbine Under Low Load Conditions

“…The Lagrange method adds a random velocity component to the velocity term of the equation of motion. In a rotating coordinate system, the equation of motion of particles derived by Basset, Boussinesq and Oseen is shown in equation (Chen, et al, 2021;Ding, et al, 2021;Wittmann, et al, 2021) Eq. 5. where m p is the particle quality, u is the velocity, ρ is the density, µ is the fluid kinematic viscosity coefficient, C D is the drag coefficient, F b is the buoyancy due to gravity, ω is the rotational angular velocity, R is the calibrate the direction vector of the rotation axis, F U is the user-defined other forces, f, p represents vapor phase and liquid respectively, t 0 is the start time, t 1 is the end time.…”