Bulletin of the American Physical Society
64th Annual Meeting of the APS Division of Fluid Dynamics
Volume 56, Number 18
Sunday–Tuesday, November 20–22, 2011; Baltimore, Maryland
Session H30: Biofluids: Phonation and Upper Airway Flows |
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Chair: Byron Erath, The George Washington University Room: Ballroom IV |
Monday, November 21, 2011 10:30AM - 10:43AM |
H30.00001: Irregular vocal fold dynamics incited by asymmetric fluid loading in a model of recurrent laryngeal nerve paralysis David Sommer, Byron D. Erath, Matias Zanartu, Sean D. Peterson Voiced speech is produced by dynamic fluid-structure interactions in the larynx. Traditionally, reduced order models of speech have relied upon simplified inviscid flow solvers to prescribe the fluid loadings that drive vocal fold motion, neglecting viscous flow effects that occur naturally in voiced speech. Viscous phenomena, such as skewing of the intraglottal jet, have the most pronounced effect on voiced speech in cases of vocal fold paralysis where one vocal fold loses some, or all, muscular control. The impact of asymmetric intraglottal flow in pathological speech is captured in a reduced order two-mass model of speech by coupling a boundary-layer estimation of the asymmetric pressures with asymmetric tissue parameters that are representative of recurrent laryngeal nerve paralysis. Nonlinear analysis identifies the emergence of irregular and chaotic vocal fold dynamics at values representative of pathological speech conditions. [Preview Abstract] |
Monday, November 21, 2011 10:43AM - 10:56AM |
H30.00002: Fluid-acoustic interactions and their impact on pathological voiced speech Byron D. Erath, Matias Zanartu, Sean D. Peterson, Michael W. Plesniak Voiced speech is produced by vibration of the vocal fold structures. Vocal fold dynamics arise from aerodynamic pressure loadings, tissue properties, and acoustic modulation of the driving pressures. Recent speech science advancements have produced a physiologically-realistic fluid flow solver (BLEAP) capable of prescribing asymmetric intraglottal flow attachment that can be easily assimilated into reduced order models of speech. The BLEAP flow solver is extended to incorporate acoustic loading and sound propagation in the vocal tract by implementing a wave reflection analog approach for sound propagation based on the governing BLEAP equations. This enhanced physiological description of the physics of voiced speech is implemented into a two-mass model of speech. The impact of fluid-acoustic interactions on vocal fold dynamics is elucidated for both normal and pathological speech through linear and nonlinear analysis techniques. [Preview Abstract] |
Monday, November 21, 2011 10:56AM - 11:09AM |
H30.00003: Dynamically Scaled Glottal Flow Through Symmetrically Oscillating Vocal Fold Models Lori Halvorson, Andrew Baitinger, Erica Sherman, Michael Krane, Lucy Zhang, Timothy Wei Experimental results derived from DPIV measurements in a scaled up dynamic human vocal fold model are presented. The 10x scale vocal fold model is a new design that incorporates key features of vocal fold oscillatory motion. This includes coupling of down/upstream rocking as well as the oscillatory open/close motions. Experiments were dynamically scaled to examine a range of frequencies, 100 -- 200 Hz, corresponding to the male and female voice. By using water as the working fluid, very high resolution, both spatial and temporal resolution, was achieved. Time resolved movies of flow through symmetrically oscillating vocal folds will be presented. Both individual realizations as well as phase-averaged data will be shown. Key features, such as randomness and development time of the Coanda effect, vortex shedding, and volume flow rate data will be shown. In this talk, effects associated with paralysis of one vocal fold will be discussed. This talk provides the baseline fluid dynamics for the vocal fold paralysis study presented in Sherman, \textit{et al}. Supported by the NIH. [Preview Abstract] |
Monday, November 21, 2011 11:09AM - 11:22AM |
H30.00004: Examination of the Vocal Fold Paralysis on the Fluid Dynamics of the Glottis Erica Sherman, Michael Krane, Lucy Zhang, Timothy Wei This talk is coupled to the symmetric vocal fold oscillation study presented in Halvorson, \textit{et al}. In this study, one of the two symmetric vocal fold models was allowed to remain rigid while the other model was driven through a normal oscillation cycle. Again, a range of reduced frequencies were studied corresponding to physiological frequencies from 100 -- 200 Hz. Flow measurements showing jet velocity and orientation, vortex shedding as a function of time through an oscillation cycle will be presented. Experimental data has been phase averaged to highlight characteristic differences between male and female voices. Additionally, volumetric flow rate and glottal behavior will be presented to show recurring features in phonation during an oscillation cycle. An example of differences between the paralysis case and the symmetrically oscillating vocal fold case is that the Coanda effect develops much more quickly and predictably for the paralysis case. Additional comparisons between diseased and healthy conditions will be presented and discussed. Supported by the NIH. [Preview Abstract] |
Monday, November 21, 2011 11:22AM - 11:35AM |
H30.00005: Experimental study of the effects of airflow and vocal fold stiffness on male and female voice production Elizabeth Campo, McPhail Michael, Krane Michael The effect of airflow in voice production is not fully understood, leading to difficulties when clinically diagnosing voice disorders. Many existing studies in this this area focus primarily on the male physiology. This study incorporates 2-layer, molded silicone vocal fold models whose geometry mimics the shape and dimensions of both male and female vocal folds. Measured quantities include subglottal and transglottal pressure, volume flow rate, and radiated sound. The results are used to clarify the relationship between glottal airflow and sound production. The Implications of the measurements for similarities and differences between male and phonation are discussed. [Preview Abstract] |
Monday, November 21, 2011 11:35AM - 11:48AM |
H30.00006: Numerical study of human vocal folds vibration using Immersed Finite Element Method Xingshi Wang, Lucy Zhang, Michael Krane The voice production procedure is a self-oscillating, fluid-structure interaction problem. In this study, the vocal folds vibration during phonation will be simulated by self-oscillated layered-structure vocal folds model, using Immersed Finite Element Method. With the numerical results, we will find out the vocal folds vibration pattern, and also show how the lung pressure, stiffness and geometry of vocal folds will affect the vocal folds vibration. With further analysis, we shall get better understanding of the dynamics of voice production. [Preview Abstract] |
Monday, November 21, 2011 11:48AM - 12:01PM |
H30.00007: Aeroacoustic simulation for phonation modeling Jeffrey Irwin, Amanda Hanford, Brent Craven, Michael Krane The phonation process occurs as air expelled from the lungs creates a pressure drop and a subsequent air flow across the larynx. The fluid-structure interaction between the turbulent air flow and oscillating vocal folds, combined with additional resonance in the oral and nasal cavities, creates much of what we hear in the human voice. As many voice-related disorders can be traced to irregular vocal tract shape or motion, it is important to understand in detail the physics involved in the phonation process. To numerically compute the physics of phonation, a solver must be able to accurately model acoustic airflow through a moving domain. The open-source CFD package OpenFOAM is currently being used to evaluate existing solvers against simple acoustic test cases, including an open-ended resonator and an expansion chamber, both of which utilize boundary conditions simulating acoustic sources as well as anechoic termination. Results of these test cases will be presented and compared with theory, and the future development of a three-dimensional vocal tract model and custom-mode acoustic solver will be discussed. [Preview Abstract] |
Monday, November 21, 2011 12:01PM - 12:14PM |
H30.00008: Estimation of aeroacoustic source strengths in phonation Michael Krane, Elizabeth Campo, Michael McPhail The underlying mechanisms of phonatory sound production are studied by quantifying the strength of the aerocoustic sources. The sources include a volume source due to vocal fold displacement, and a dipole related to the transglottal pressure difference. The challenges involved with estimating these sources in a resonator are addressed. Measurements of flow-induced vibration and sound produced by life-scale, 2-layer silicone rubber model vocal folds were conducted in a physical model of the human airway. Measurements, including transglottal pressure, radiated sound, and high-speed imaging of the model glottis, were used to produce estimates of the strengths of volume and dipole sources. [Preview Abstract] |
Monday, November 21, 2011 12:14PM - 12:27PM |
H30.00009: Epiglottal Flow Physics Andrew Pollard, Abdul-Monsif Shinneeb PIV measurements have been made at three locations in the pharynx/larynx region in the ETA model, one along the central sagittal plane and two cross-sectional planes. The measurements were made at a flow rate of 9.04 l/min which corresponds approximately to 10 l/min in the prototype. The corresponding Reynolds number Re based on the inlet condition is 716. Two thousand images were acquired at each location at a framing rate of 2 Hz. The mean velocity fields were then calculated. In addition,the data was analysed by the proper orthogonal decomposition (POD) technique to expose vortical structures. Only few modes were used for the POD reconstruction which recovered about 60\% of the turbulent kinetic energy. The results showed that the flow is characterised by regions of re-circulation, jet-like, and sink-like flows. In addition, the POD-reconstructed fields revealed some interesting features that occur in the human pharynx/larynx region near the epiglottis such as tearing and pairing processes, as well as the interaction between the flows induced by the structures. [Preview Abstract] |
Monday, November 21, 2011 12:27PM - 12:40PM |
H30.00010: Numerical simulation of transitional flow in a human upper airway segment in the presence of uncertainty Olaf Marxen The flow in human airways may be laminar, transitional, or turbulent in different airway segments. Specifically, laminar-turbulent transition is believed to occur in the larynx or in the trachea. Present approaches to simulate such flows typically employ numerical methods solving the steady Reynolds-averaged Navier-Stokes equations. However, natural airway deformations or pathological obstructions such as tumors may generate recirculation zones and lead to highly unsteady flow features that are not well captured by these numerical methods. We perform direct numerical simulations of transitional flow through a pipe-like canonical geometry representative of an airway segment. The incompressible Navier-Stokes equations in conjunction with an immersed boundary method are solved to simulate the unsteady flow. In order to model perturbations present in the incoming flow, small-amplitude disturbances are forced to explicitly trigger flow instabilities. Time-dependent inflow profiles are applied to model the change in flow velocity during the breathing process. In order to account for natural variability during breathing, the inflow profile is treated as an uncertain function. Resulting uncertainty in the flow field is quantified using stochastic collocation. [Preview Abstract] |
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