title: Visualization of flow resistance in physiological nasal respiration: analysis of velocity and vorticities using numerical simulation.
abstract: OBJECTIVE
  To visualize the velocity gradients and the vorticities of physiological unsteady nasal flow using the computational fluid dynamics method and to compare the inspiratory phase and expiratory phase flow patterns.
  
  
  METHODS
  An anatomically correct 3-dimensional nasal and pharyngeal cavity was constructed from computed tomographic images of a healthy adult nose and pharynx. The unsteady state Navier-Stokes and continuity equations were solved numerically on inspiratory and expiratory nasal flow.
  
  
  METHODS
  Numerical simulation application.
  
  
  METHODS
  Coronary and axial computed tomographic images from a healthy adult were used.
  
  
  METHODS
  The detailed velocity distribution and vorticity (resistance) distribution of nasal airflow were visualized using the computational fluid dynamics method (an imaging technology for regional flow factors [velocity, vector, streamline, and vortex]).
  
  
  RESULTS
  In the inspiratory phase, a high-velocity area was prominent in the middle meatus, and the highest vorticity area had good agreement with this region. In the expiratory phase, the distributions of velocity and vorticities were flatter than those in the inspiratory phase.
  
  
  CONCLUSIONS
  The computational fluid dynamics model allows the investigation of airflow elements under physiological conditions, as well as the examination of the effect of nasal structure.
authors.affiliation: Department of Otolaryngology, Kanazawa Municipal Hospital, Kanazawa, Japan. ishikawa@po.incl.ne.jp
authors.forename: Shigeru
authors.initials: S
authors.lastname: Ishikawa
authors.forename: Toshio
authors.initials: T
authors.lastname: Nakayama
authors.forename: Masahiro
authors.initials: M
authors.lastname: Watanabe
authors.forename: Teruo
authors.initials: T
authors.lastname: Matsuzawa
mesh_terms: D000403:Airway Resistance / Q000502:physiology*; D003198:Computer Simulation; D006801:Humans; D009296:Nasal Cavity / Q000502:physiology*; D010614:Pharynx / Q000502:physiology*; D012143:Respiratory Physiological Phenomena; D014057:Tomography, X-Ray Computed