Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 150554

150554 - Effects of Inflow Conditions on the Aerosol Deposition Characteristics in Human Airways 

Several of the pulmonary diseases such as asthma, cystic fibrosis, pulmonary infection, lung tumors, etc., can be treated by employing aerosolized drug delivery. Therefore, an improved regional deposition of the inhaled drug is key to maximizing its efficiency and minimizing its side effects. Although recent advancements in radiological imaging techniques have enabled an objective assessment of the phenotype of airways and other anatomical features through in vivo and in vitro measurements, the information required for an effective treatment procedure remains limited. To this end, computational tools can be immensely useful in predicting airflow and aerosol deposition in respiratory airways. In this study, we employ high-fidelity large-eddy simulation (LES) as a computational tool to examine the airflow and aerosol dynamics in a realistic human airway.

 

Aerosol deposition within human airways corresponds to the broader category of dispersed multiphase flows, which comprise a carrier phase (airflow) and a disperse phase (aerosol). Such flows can be classified as a dilute suspension, a dense suspension, or a granular flow depending upon the mass and the volume loading of the dispersed phase. In this study, we consider a dilute suspension approximation with a one-way coupling, where only the carrier phase flow affects the dynamics of the aerosol. To perform LES-based studies, we employ the well-established Eulerian-Lagrangian (EL) framework. In this approach, the carrier phase is simulated using the Eulerian approach and the dispersed phase is treated as a point particle and evolved in a Lagrangian manner. Such an approach allows an easier description of particle evolution, turbulence dispersion, polydispersity, and collision of particles with the airway walls.

 

The computational model considers a truncated portion of a realistic human airway model based on the SimInhale benchmark case. This model includes the extrathoracic and a portion of the intrathoracic airways. First, we demonstrate the adequacy of the computational framework by comparing it with reference experimental and numerical results. This is accomplished by simulating the flow at bulk Reynolds number of 3745 and injecting a stream of particles with a diameter of 4.3 μm. Specifically, we compare the results for the flow field in terms of the instantaneous and time-averaged turbulence statistics at different cross-sectional planes of the upper airway. For the aerosol, we compare the local and global deposition fractions of particles. The next part of the study focuses on examining the effects of inflow conditions on the aerosol deposition patterns. We compare two distinct inflow conditions, namely, a uniform bulk inflow velocity with a bulk Reynolds number of 3745 and a time-varying sinusoidal inflow velocity with the same bulk velocity. The time-varying inflow condition is designed to simulate the physiological processes of inhalation and exhalation within the airway. We consider three non-interacting particle streams with fixed diameters of 1 μm, 5 μm, and 10 μm to characterize the effects of the Stokes number on the deposition of particles under the two inflow conditions.

Presenting Author: Jacob Pratt University of Tennessee at Chattanooga

Presenting Author Biography: Jacob Pratt is a graduate assistant at the University of Tennessee at Chattanooga, conducting research in computational fluid dynamics with a focus on biomedical applications. Working under the guidance of Dr. Reetesh Ranjan, his work is supported by the National Science Foundation. His research aims to enhance our understanding of fluid behaviors in medical applications.

Authors:

Jacob Pratt University of Tennessee at Chattanooga
Reetesh Ranjan University of Tennessee at Chattanooga