Direct numerical simulations of impulsively started jets with application to speech production

Abstract

Many aspects of the conversion of the air flow through the larynx into sound are still insufficiently understood for the purposes of making precise diagnostic decisions in the voice clinic, targeting optimal intervention strategies for voice problems and voice training, and achieving high-quality articulatory speech synthesis. In a previous study, experiments performed using a dynamic physical model of the larynx revealed the presence of a transient pulse occurring immediately after the instant of vocal fold separation, prior to the formation of a quasisteady developing jet [Mongeau et al., J. Acoust. Soc. Am. 102, 1121–1133 (1997)]. The purpose of the present study was to investigate this phenomenon numerically using direct and large eddy simulations of an impulsively started free planar jet. The compressible Navier–Stokes equations were integrated using a two–four compact finite-difference scheme. A nonuniform Cartesian grid was used with Navier–Stokes characteristic boundary conditions. Preliminary results confirmed the presence of an acoustic pulse immediately following the imposition of a pressure gradient across the orifice. The feasibility of extending this conclusion for the case of three-dimensional confined jets will be discussed. [Work supported by NIH.]