Matematické a fyzikální modelování prouděním vyvolaného kmitání lidských hlasivek

the pressure and velocity fields in coronal plane along the vibrating vocal folds were studied using a finite element mathematical model. The shapes of the vocal folds were specified according to data measured on excised human larynges in phonation position. The mathematical model of the flow is based on 2D incompressible Navier-Stokes equations adapted to deal with the time-variable shape of the domain, caused by vocal fold vibration. The numerical simulations allow to observe closely various flow features related to phonation - flow separation in the glottis, Coanda effect or vortex shedding

Coherent turbulent structures in flow through the human vocal tract

This paper presents experimental and computational data on the coherent turbulent structures in flow through the human vocal tract. The experimental results were obtained using a 4:1 scaled self-oscillating physical model of vocal folds. Flow velocity fields in the coronal plane were visualized and measured using a PIV system phase-synchronized with vocal fold vibration. Computational results originate from finite volume discretizations of viscous incompressible Navier-Stokes equations in 2D and 3D. The results reveal flow separation in the divergent part of glottis and formation of a planar jet. Vortex structures are shed from the shear layer of the jet and convected further downstream. The computational model helps to assess the influence of the ventricular folds on the flow patterns

Matematické modelování interakce tekutiny a tělesa v problematice lidských hlasivek

In the paper numerical results from a mathematical model of human vocal folds are compared with experimental data obtained from measurements on a maquette of vocal folds, which consisted of a silicone element vibrating in a channel conveying air

Interakce tělesa a tekutiny v lidských hlasivkách

Matematicko-fyzikální fakultaFaculty of Mathematics and Physic

Dynamic properties of some physical models of artificial vocal folds

The report presents results from measurements of acoustic and vibratory characteristics of six originally designed artificial vocal fold prototypes made of silicon rubber and based on various aeroelastic principles. During measurements, the dynamic subglottal pressure and output acoustic pressure were recorded. Spectral analysis of the signals was performed, and where the construction permitted, the vibrations were also observed by means of videostroboscopy. For two prototypes a shape and material optimization is possible with the aid of the mathematical models developed in IT AS CR

Computational aeroacoustics of human phonation

The current paper presents a CFD model of flow past vibrating vocal folds coupled to an acoustic solver, which calculates the sound sources from the flow field in a hybrid approach. The CFD model is based on the numerical solution of 3D Navier-Stokes equations on a time-dependent domain, solved by cell-centered finite volume method. To capture the fine turbulent scales important for the acoustic source calculations, the equations are discretized and solved on large computational meshes up to 3.2M elements. The CFD simulations were run in parallel using domain decomposition method and OpenMPI implementation of the MPI standard. Aeroacoustic simulations are calculated in a separate step by Lighthill’s acoustic analogy, which determines the acoustic sources based on the fluid field. This is done with the research code CFS++ which employs the finite element method (FEM)

Large eddy simulation of airflow in human vocal folds

Human phonation is a complex physiological process involving flow-induced oscillations of the vocal folds and aeroacoustic sound generation. The flow fields encountered in phonation are highly unsteady, feature massive flow separation and recirculation in the supraglottal spaces and generation of coherent vortex structures from the shear layer of the jet. For the sake of computational aeroacoustic modeling of human voice generation, an accurate resolution of the airflow through the vocal folds is essential. The Reynolds-averaged Navier-Stokes turbulence modeling is inappropriate, since it provides only the averaged flow field. The paper presents the first results obtained with a large-eddy simulation of flow through a model of human vocal folds using a second-order finite volume discretization of incompressible Navier-Stokes equations. In the first step, the flow field was resolved on a fine 2D mesh covering a short subglottal region, the glottis and a part of the supraglottal channel. The simulation was parallelized using domain decomposition method and run in parallel on a shared-memory supercomputer. The results compare two large eddy simulations using the algebraic Smagorinsky and one-equation sub-grid scale models against a simulation without turbulence model