Unsteady laryngeal airflow simulations: An analysis of the generated intraglottal vortical structures.

Unsteady flow simulations in diffuserlike vocal‐fold models proved that laryngeal airflow generates vortical structures in the intraglottal region. However, the features of these vortices and their influence on the vocal‐fold motion were not clearly addressed. The present work characterizes the intraglottal vortical structures developed during the closing phase of the phonation cycle in order to analyze their possible influence on the voice quality. It is shown that intraglottal vortices are formed on the divergent slope of the glottis, just downstream of the separation point. The core of the vortical structures is characterized by important negative static pressure values (lower as compared with the surrounding pressure field). These vortices gain strength and increase in size as are convected downstream by the flow. The mechanism for which the intraglottal flow structures are becoming stronger is attributed to the entrained air from the supraglottal region. The instantaneous pressure loads on the divergent glottal slope are not uniform (in both time and space) and dependent on the vortical structures traveling nearby the glottis. The negative static pressures associated with the intraglottal vortical structures suggest that the closing phase during phonation may be accelerated by such vortices.