Recent advances and key challenges in investigations of the flow inside human oro-pharyngeal-laryngeal airway

Abstract

The oro-pharyngeal-laryngeal human airway is a complex geometry; the flow physics within are subjected to and influenced by a variety of different factors that produce jet-like flow, re-circulating flows that are enhanced by curvature, detached and secondary flows. Simulation and experiment are the tools available to the fluid dynamics researcher. Simulation results obtained from direct and large-eddy simulation, and Reynolds-averaged Navier–Stokes and associated models of turbulence are reviewed. Experimental data obtained through the use of flow visualisation, hot-wire anemometry and particle image velocimetry are also reviewed. A comparison of data obtained from the application of these tools reveals many inconsistencies that are explored in this article. While much progress has been made to understand some of the physics of the flow in the human airway, we continue to uncover new and significant fluid dynamic behaviour. Finally, future research directions are suggested.