A Coupled CFD-FEM Investigation of Fluid-Structure-Acoustic Interactions with Contact Mechanics

Many natural and technical systems are governed by the interaction of deformable structures with fluid flows and acoustic waves. The accurate description, modelling, and simulation of such systems, which is based on the theory of continuum mechanics, is therefore of special importance in many fields of science and engineering. This thesis focuses on the theoretical framework that allows the mathematical and physical representation of Fluid-Structure-Acoustic Interaction (FSAI) and the practical application of these techniques to a strongly-coupled system, which is the process of phonation. Phonation provides a rich test case for modelling and simulation of FSAI, due to the presence of complex fluid and structural behaviours, such as transitional flow, turbulence, nonlinear materials, large deformations, and mechanical contact. The first of two computational cases investigates Large Eddy Simulation (LES) of airflow through a vocal fold model using prescribed deformations, with special attention on the aero- and vibroacoustic sound-generation mechanisms. The second case focuses on the interaction of the air with the mechanically deforming and contacting solid and explores a strongly two-way coupled model. Studying both cases allows for a deep understanding of all aspects of the physical processes underlying the phonatory process. The accurate computational description of phonation through three-dimensional, two-way-coupled simulations that include mechanical contact of the vocal folds has long been infeasible. This work, building on decades of continuum mechanical, numerical, and phonatory research, thus provides a comprehensive framework for the next generation of high-fidelity, predictive models of human phonation.