Bulletin of the American Physical Society
2005 58th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 20–22, 2005; Chicago, IL
Session HA: Bio-Fluid Dynamics: Vocal and Oral |
Hide Abstracts |
Chair: Timothy Wei, Rutgers University Room: Hilton Chicago International Ballroom South |
Monday, November 21, 2005 1:20PM - 1:33PM |
HA.00001: Flow Field of a Human Cough Jean Hertzberg, Julie Meg VanSciver, Shelly Miller Cough generated infectious aerosols are of interest while developing strategies for the mitigation of disease risks ranging from the common cold to SARS. In this work, the velocity field of human cough was measured using particle image velocimetry (PIV). The project subjects (total 29) coughed into an enclosure seeded with stage fog for most measurements. Cough flow speed profiles, average widths of the cough jet, waveform, and maximum cough speeds were measured. Maximum cough speeds ranged from 1.5 m/s to 28.8 m/s. No correlation was found for maximum cough flow speeds to height or gender. The slow growth of the width of the cough flow suggests that a cough may penetrate farther into a room than a steady jet of similar volume. The velocity profile was found to scale with the square root of downstream distance. [Preview Abstract] |
Monday, November 21, 2005 1:33PM - 1:46PM |
HA.00002: Computational aeroacoustics of human vocal tract model flow Jungsoo Suh, Steven Frankel, Luc Mongeau, Michael Plesniak Computational aeroacoustics studies of flow through the human vocal tract, here modeled as a planar channel with an orifice, hence referred to as the glottis, are conducted using large eddy simulation (LES). Comparisons between LES predictions and experimental wall pressure measurements and particle-imaging-velocimetry flow fields will be presented. The compressible Navier-Stokes equations are accurately and efficiently integrated for the low Mach number flow through the use of an additive semi-implicit Runge-Kutta method and high-order compact finite-difference schemes for spatial discretization. Characteristic-based non-reflecting boundary conditions are used together with an exit zone in the context of a multi-block approach. An acoustic analogy based on the Ffowcs Williams--Hawkings equation will be applied to decompose the near-field acoustic source into its monopole, dipole, and quadrupole contributions to assess glottal geometry effects on far-field sound. [Preview Abstract] |
Monday, November 21, 2005 1:46PM - 1:59PM |
HA.00003: Velocity field measurements in oblique static divergent vocal fold models Byron Erath, Michael Plesniak During normal phonation, the vocal fold cycle is characterized by the glottal opening transitioning from a convergent to a divergent passage and then closing before the cycle is repeated. Under ordinary phonatory conditions, both vocal folds, which form the glottal passage, move in phase with each other, creating a time-varying symmetric opening. However, abnormal pathological conditions, such as unilateral paralysis, and polyps, can result in geometrical asymmetries between the vocal folds throughout the phonatory cycle. This study investigates pulsatile flow fields through 7.5 times life-size vocal fold models with included divergence angles of 5 to 30 degrees, and obliquities between the vocal folds of up to 15 degrees. Flow conditions were scaled to match physiological parameters. Data were taken at the anterior posterior mid-plane using phase-averaged Particle Image Velocimetry (PIV). Viscous flow phenomena including the Coanda effect, flow separation points, and jet “flapping” were investigated. The results are compared to previously reported work of flow through symmetric divergent vocal fold models. [Preview Abstract] |
Monday, November 21, 2005 1:59PM - 2:12PM |
HA.00004: Experimental study of the flow-induced vibration of a flexible duct constriction B. Cohen, M. Krane, T. Wei Rutgers University, Piscataway, NJ Benjamin Cohen, Michael Krane, Timothy Wei Measurements of the motion of a flexible-walled duct constriction and the flow with which it interacts are presented. The current study focuses on proof-of-concept of the measurement technique for studying the fully-coupled flow-induced vibration of scaled-up models of the human vocal folds. The constriction model is a pair of sheets of visco-elastic material, each bent into a horseshoe shape. Video image sequences record of the wall and flow tracer particles in the flow. The flow velocity field is estimated using a DPIV processing technique. An edge detection scheme is used to find the shape of the wall in each image. From these measurements, a single cycle of vibration is constructed. The modes of vibration of the wall are shown, as well as the structure of the jet issuing from the downstream side of the constriction. It is shown that both the flow and the motion of the wall can be characterized sufficiently to allow estimates of the energy exchange between the flow and the structure. [Preview Abstract] |
Monday, November 21, 2005 2:12PM - 2:25PM |
HA.00005: Inherent unsteadiness of glottal flow Michael Krane, Michael Barry, Timothy Wei This talk describes a test of the quasisteady glottal flow assumption, a fundamentally relevant question which has implications on the glottal impedance and on how aerodynamics may affect voice perturbations and fluctuations. Measurements of the flow velocity field in a scaled-up model of the human glottis are described which used Digital Particle Image Velocimetry during several cycles of model vocal fold motion. Flow data thus obtained were used to calculate waveforms of the unsteady and convective acceleration terms for a single cycle of vocal fold motion. These calculations demonstrate that (1) over the entire glottis, the unsteady acceleration is important throughout the vibration cycle, (2) that the jet flow is primarily responsible for the high levels of unsteady acceleration in glottal flow, and (3) vortex shedding is responsible for high-frequency contributions to both types of acceleration. Measurements made at four cycle frequencies show the frequency dependence of these results. These results all suggest that (1) the quasisteady assumption is highly suspect and (2) jet instability (vortex shedding) strongly influences glottal impedance. This last observation also suggests that glottal jet aerodynamics may contribute strongly to voice perturbations and fluctuations. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700