Evaluation of aerodynamic characteristics of a coupled fluid-structure system using generalized Bernoulli's principle: An application to vocal folds vibration

Abstract

In this work we explore the aerodynamics flow characteristics of a coupled fluid-structure interaction system using a generalized Bernoulli equation derived directly from the Cauchy momentum equations. Unlike the conventional Bernoulli equation where incompressible, inviscid, and steady flow conditions are assumed, this generalized Bernoulli equation includes the contributions from compressibility, viscous, and unsteadiness, which could be essential in defining aerodynamic characteristics. The application of the derived Bernoulli’s principle is on a fully-coupled fluid-structure interaction simulation of the vocal folds vibration. The coupled system is simulated using the immersed finite element method where compressible Navier-Stokes equations are used to describe the air and an elastic pliable structure to describe the vocal fold. The vibration of the vocal fold works to open and close the glottal flow. The aerodynamics flow characteristics are evaluated using the derived Bernoulli’s principles for a vibration cycle in a carefully partitioned control volume based on the moving structure. The results agree very well to experimental observations, which validate the strategy and its use in other types of flow characteristics that involve coupled fluid-structure interactions.

Cycle-to-cycle flow variations in a square duct with a symmetrically oscillating constriction

“…The specific goal of this paper is to leverage spatially and temporally resolved measurements in clinical, science-based, computational modeling of voice disorders. This is part of a joint computational-experimental effort where similar data analysis is being done computationally, (Zhang and Yang 2016, Yang et al 2017, Zhang et al 2019, and in life-scale physical models, McPhail et al (2019).…”

A deep-learning based generalized reduced-order model of glottal flow during normal phonation

“…Yet, the inviscid assumption has made the model inaccurate in predicting the glottal flow rate and intraglottal pressures, especially during glottal closing when the glottis is typically in a divergent shape in which rich viscous effects occur such as flow separation, shear layer instability and intraglottal vortices (Deverge et al, 2003;Pelorson et al, 1994;Scherer et al, 1983). To improve the accuracy, research efforts have been made to incorporate various viscous loss terms into the Bernoulli equation (Deverge et al, 2003;Ishizaka and Flanagan, 1972;Van den Berg et al, 1957;Zhang and Yang, 2016). While the results showed improvement over the original Bernoulli equation, the modified model is largely based on assumptions of simple glottal shapes.…”