title: Dynamics of airflow in a short inhalation.
abstract: During a rapid inhalation, such as a sniff, the flow in the airways accelerates and decays quickly. The consequences for flow development and convective transport of an inhaled gas were investigated in a subject geometry extending from the nose to the bronchi. The progress of flow transition and the advance of an inhaled non-absorbed gas were determined using highly resolved simulations of a sniff 0.5 s long, 1 l s⁻¹ peak flow, 364 ml inhaled volume. In the nose, the distribution of airflow evolved through three phases: (i) an initial transient of about 50 ms, roughly the filling time for a nasal volume, (ii) quasi-equilibrium over the majority of the inhalation, and (iii) a terminating phase. Flow transition commenced in the supraglottic region within 20 ms, resulting in large-amplitude fluctuations persisting throughout the inhalation; in the nose, fluctuations that arose nearer peak flow were of much reduced intensity and diminished in the flow decay phase. Measures of gas concentration showed non-uniform build-up and wash-out of the inhaled gas in the nose. At the carina, the form of the temporal concentration profile reflected both shear dispersion and airway filling defects owing to recirculation regions.
authors.forename: A J
authors.initials: AJ
authors.lastname: Bates
authors.forename: D J
authors.initials: DJ
authors.lastname: Doorly
authors.forename: R
authors.initials: R
authors.lastname: Cetto
authors.forename: H
authors.initials: H
authors.lastname: Calmet
authors.forename: A M
authors.initials: AM
authors.lastname: Gambaruto
authors.forename: N S
authors.initials: NS
authors.lastname: Tolley
authors.forename: G
authors.initials: G
authors.lastname: Houzeaux
authors.forename: R C
authors.initials: RC
authors.lastname: Schroter
mesh_terms: D001980:Bronchi / Q000502:physiology; D003198:Computer Simulation; D005740:Gases; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D008962:Models, Theoretical; D009333:Neck / Q000000981:diagnostic imaging; D012123:Pulmonary Ventilation; D013902:Radiography, Thoracic; D012119:Respiration; D013314:Stress, Mechanical; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D005740:Gases