Tracking Vortex Dipolar Structures in a Laryngeal-Like Jet

Abstract

A vortex dipole is a couple of two closely-packed counter-rotating circulations which is usually observed in geophysical flows, in tidal channels and in laboratory flows using stratifed fluids, shallow water, soap films or slitted nozzles. The glottis, defined by the aperture between the vocal folds, takes the shape of a size-varying slit during voice production. The vocal folds configure the first of two constrictions encountered by the flow through the human larynx. If the so-called false vocal folds are sufficiently adducted, a second slit is present. These geometrical conditions favor the roll-up of vortex dipolar structures as the laryngeal jet is formed at the slits. In this work, we present direct numerical simulations and laboratory experiments for simple (static and rigid) and complex (dynamic and elastic) models of the vocal folds. The simple model is used to do the register of the possible types of vortex dipoles which form and evolve during a fluid transient compatible with vocal fold opening. Vortex dipolar structures are then tracked in flow visualizations for models of increasing complexity. Three-dimensional numerical simulations appear as necessary to gain further insight on the mechanisms in play.