Fluid-Structure Interaction of Human Upper Airways

Abstract

This thesis investigates the fluid-structure interaction (FSI) of a Starling Resistor to understand the mechanics behind wheezing, which is a common respiratory symptom. By using a combination of computational fluid dynamics (CFD) and structural analysis, the study applies a partitioned FSI approach to simulate the interaction between airflow and a Starling Resistor. The results of this study present the first valid FSI simulation that models wheezing. In addition, the research investigates how changes in the shape of airways, particularly narrowing in the middle part, affect the flow speed and distribution of pressure. The simulations show how air moves and how the structures change, capture the frequency of the onset of tube’s oscillations. The results suggest that the increase in pressure at the inlet of the tube in combination with the external pressure that act on the tube, is the primary mechanism causing the tube’s oscillations. This study provides valuable insights into how fluids and structures interact in collapsible airways and contributes to the broader field of respiratory mechanics, especially for wheezing. The results could help in developing better tools for diagnosis and strategies for treating respiratory conditions. Also, future work could focus on improving the simulation models by using more advanced mesh designs, models that account for turbulent flow, finer time steps to accurately capture the exact start and frequency of tube movement and an improvement of signal processing to analyze the tube oscillations with a wavelet process. These improvements could lead to more precise and predictive models, ultimately benefiting both clinical practice and patient diagnoses.