Computational Fluid Dynamics Laboratory

LES of Human Vocal Tract Model Flow

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.

Our previous work involved two-dimensional, axisymmetric aeroacoustics simulations of a model human vocal tract. By excluding the effects of turbulence (recall vortex stretching is identically zero in two-dimensions) we were able to include wall motion (one-way fluid-structure interaction - actual phonation involves flow-induced oscillations of the vocal folds). Animation of vorticity in model vocal tract with driven glottis.

For more information on this project and related vocal tract studies please see the main project webpage at: Voice Project (click on animations for some of our previous simulation work).

  1. Grid used for human vocal tract model flow; color shows computational blocks in multi-block simulation.

  2. Instantaneous vortical structure near the glottis of human vocal tract model indentified by second invariant Q=0.05; colored by streamwise velocity.

  3. Animation of streamwise velocity showing turbulent transition, jet flapping, and Coanda Effect

    (Click here for avi file)

  4. Animation of dilatation showing acoustic wave propagation

    (Click here for avi file)
Prof. Frankel's MAIN PAGE