An experimental investigation to model wheezing in lungs

Abstract

A quarter of the world's population experience wheezing. These sounds have been used for diagnosis since the time of the Ebers Papyrus ( ca 1500 BC). We know that wheezing is a result of the oscillations of the airways that make up the lung. However, the physical mechanisms for the onset of wheezing remain poorly understood, and we do not have a quantitative model to predict when wheezing occurs. We address these issues in this paper. We model the airways of the lungs by a modified Starling resistor in which airflow is driven through thin, stretched elastic tubes. By completing systematic experiments, we find a generalized ‘tube law’ that describes how the cross-sectional area of the tubes change in response to the transmural pressure difference across them. We find the necessary conditions for the onset of oscillations that represent wheezing and propose a flutter-like instability model for it about a heavily deformed state of the tube. Our findings allow for a predictive tool for wheezing in lungs, which could lead to better diagnosis and treatment of lung diseases.

Sound generation mechanisms in a collapsible tube

“…where E is the Young's modulus and is the Poisson ratio. The values of these elastic parameters are the same as the samples used in Gregory et al (2021), whose experimental data will be used to validate the numerical results (E ¼ 10 6 Pa, ¼ 0.49, q ¼ 1000 kg/m 3 ).…”

“…Numerical models based on CFD simulation with the ambition to provide a reliable quantitative analysis need to be experimentally validated. The possibility to access the large amount of independent highquality experimental data (Bertram, 2003;Gregory et al, 2021;Zarandi et al, 2021) targeting collapsible tubes under different conditions makes the validation step possible and reliable. Moreover, by reducing the complexity of a biological system to its very fundamental parts, it is possible to identify the main physical mechanisms driving its dynamics.…”

“…The fluid behavior in a collapsible tube under different collapse scenarios has been extensively studied from theoretical (Shapiro, 1977), numerical (Heil, 1997), and experimental (Gregory et al, 2021) points of view. However, understanding the relation between the tube's characteristic flow structures and the corresponding acoustic features remains an open query.…”

Time-Dependent Fluid-Structure Interaction Simulations of a Simplified Human Soft Palate

“…The main advantage of employing simpler geometries is that the fundamental physical behaviour of the system clearly emerges and can be more easily controlled [16]. Moreover, as numerical models require validation, it is much simpler to find in literature highquality experimental data sets to validate the numerical results [17]. Tetlow & Lucey [18] modelled the soft palate as a cantilevered flexible plate placed within a unsteady, viscous, incompressible channel flow to mimic the mechanical process for the dynamics of the soft palate in OSA.…”

Computational Analysis of Active and Passive Flow Control for Backward Facing Step

“…Fluid structure interaction (FSI) involving elastic membranes [14] has been extensively studied in biomedical cases and other settings [15][16][17][18]. The steady flow in a 2D channel with one rigid plate, and another with a part of it replaced by an elastic membrane, is perturbed and the resulting flow is studied by Luo and Pedley [19].…”