The flow inside an idealised form of the human extra-thoracic airway

The mean and RMS axial velocity field in the central sagittal plane of an idealized representation of the human extrathoracic airway (ETA) during steady inspiration was studied experimentally using single and X-hot-wire anemometry (HWA). Complementary flow-visualization results illustrate the complex nature of this flow, which includes several regions of separated, secondary, and recirculating flow. Hot-wire experiments attest to this complexity, with several regions of high localized turbulence intensity measured distal to the oropharynx. Physiologically accurate flow rates of 10, 15, 30, 45, 60, 90 and 120 l/min are considered. These flow rates encompass a wide range of respiratory patterns, from normal breathing to the rapid inhalation typically encountered during the use of pharmaceutical aerosol inhalation devices.