Coherent structures in the vocal tract and speaking jet: Simulation with anatomically accurate geometry*

Aerosolized particles emanating from the vocal tract are dispersed by a pulsed jet during speaking and breathing. The intricacies of the anatomically accurate vocal tract geometry and changes in flow rate create a wide range of turbulent scales both in the tract and jet. Geometrically-resolving large-eddy simulation with the curvilinear immersed boundary method is employed to capture the disparate internal flow and external speaking jet of a physically realistic vocal tract. We investigate the evolution of coherent structures of both steady and pulsating jets for breathing and speaking. We observe complex coherent structures and recirculation zones across disparate scales. Large structures are generated in the glottis and modified by the pharynx and oral cavity. The coherence and dominant structures are quantified with spectral analysis and proper orthogonal decomposition. Turbulent statistics of the speaking jet are compared to those of a canonical turbulent jet. The analysis reveals that the effects of geometry lead to various regions of high vorticity and the presence of coherent structures.