Inhalability of micron particles through the nose and mouth

Aspiration efficiencies from nose and mouth inhalations are investigated at low and high inhalation rates by using the commercial Computational Fluid Dynamics (CFD) software CFX 11. A realistic human head with detailed facial features was constructed. Facial features were matched to represent the 50th percentile of a human male, aged between 20 and 65 years old, based on anthropometric data. The constant freestream velocity was 0.2 ms−1, normal to the face, and inhalation rates through the mouth and nose were 15 liters per minute (LPM) for light breathing and 40 LPM for heavy breathing. It was found that the flow field in the near breathing region exhibited vertical direction caused by the presence of the torso where the airstream diverges as it flows around and over the body. The critical area concept was used as a tool to determine the aspiration efficiency of particles. Comparisons between critical areas for the nose and mouth inhalations show similar geometric properties such as the area’s shape, and its vertical distance location on the x-z plane located at y = 80 cm upstream. The critical area sizes were found to be slightly larger for the mouth inhalation mainly due to the larger mouth area and also the aligned orientation of the mouth to the upstream flow, whereas the nose is perpendicular to the upstream flow. This study was undertaken to establish the flow field in the near breathing region that will help to characterize the flow and particle field for initial boundary conditions leading to a more holistic modeling approach of respiration through the internal nasal cavity and mouth.

[1]  D. Dunn-Rankin,et al.  Experimental investigation of a two-dimensional cylindrical sampler , 1994 .

[2]  R. Cuthbert,et al.  A study on dust emission, particle size distribution and formaldehyde concentration during machining of medium density fibreboard. , 2000, The Annals of occupational hygiene.

[3]  W. J. Mitchell,et al.  Airflow Around a Child-Size Manikin in a Low-Speed Wind Environment , 2003 .

[4]  Jiyuan Tu,et al.  Effect of ventilation design on removal of particles in woodturning workstations , 2009 .

[5]  G. Ahmadi,et al.  Computational modelling of gas-particle flows with different particle morphology in the human nasal cavity , 2009 .

[6]  S. Thangam,et al.  Analysis of an RNG based turbulence model for separated flows , 1992 .

[7]  Serap Erdal,et al.  Human head model as an aerosol sampler: Calculation of aspiration efficiencies for coarse particles using an idealized human head model facing the wind , 1995 .

[8]  C. N. Davies.  Inhaled Particles IV , 1972 .

[9]  Henrik Brohus,et al.  Personal Exposure to Contaminant Sources in Ventilated Rooms , 1997 .

[10]  C Kleinstreuer,et al.  Targeted drug aerosol deposition analysis for a four-generation lung airway model with hemispherical tumors. , 2003, Journal of biomechanical engineering.

[11]  P. Durbin.  SEPARATED FLOW COMPUTATIONS WITH THE K-E-V2 MODEL , 1995 .

[12]  A R Tilley,et al.  THE MEASURE OF MAN AND WOMAN , 1993 .

[13]  R A Guilmette,et al.  Effect of flow rate on particle deposition in a replica of a human nasal airway. , 2001, Inhalation toxicology.

[14]  Jeffry D. Schroeter,et al.  Fundamental Effects of Particle Morphology on Lung Delivery: Predictions of Stokes' Law and the Particular Relevance to Dry Powder Inhaler Formulation and Development , 2002, Pharmaceutical Research.

[15]  A. Bird.  Use of Numerical Calculations to Simulate the Sampling Efficiency Performance of a Personal Aerosol Sampler , 2005 .

[16]  Clement Kleinstreuer,et al.  Numerical simulation of mixed convection heat and mass transfer in a human inhalation test chamber , 2001 .

[17]  Henrik Brohus,et al.  CFD Models of Persons Evaluated by Full-Scale Wind Channel Experiments , 1996 .

[18]  S. Ding,et al.  Airway geometry and inhalation effort comparisons in a narrowed and recovered airway tree associated with acute asthma , 2008, 2008 International Conference on Audio, Language and Image Processing.

[19]  Shuzo Murakami,et al.  Study on inhalation region by means of CFD analysis and experiment , 2005 .

[20]  Michael R Flynn,et al.  CFD model for a 3-D inhaling mannequin: verification and validation. , 2006, The Annals of occupational hygiene.

[21]  L Armbruster,et al.  Investigations into defining inhalable dust. , 1982, The Annals of occupational hygiene.

[22]  T Renée Anthony,et al.  Evaluation of facial features on particle inhalation. , 2005, The Annals of occupational hygiene.

[23]  Thomas Heistracher,et al.  Local particle deposition patterns may play a key role in the development of lung cancer. , 2003, Journal of applied physiology.

[24]  Yehuda Salu,et al.  Turbulent diffusion from a quasi-kinematical point of view , 1977 .

[25]  X. Baur,et al.  Increased Incidence of DNA Double-Strand Breaks in Lung and Liver of Rats After Exposure to Crocidolite Asbestos Fibers , 1994 .

[26]  S. Ding,et al.  Comparative Study of the Effects of Acute Asthma in Relation to a Recovered Airway Tree on Airflow Patterns , 2009 .

[27]  Michael R. Flynn,et al.  Computational fluid dynamics investigation of particle inhalability , 2006 .

[28]  J H Vincent,et al.  Applications of blunt sampler theory to the definition and measurement of inhalable dust. , 1982, The Annals of occupational hygiene.

[29]  David L. Swift,et al.  THE MEASUREMENTS OF HUMAN INHALABILITY OF ULTRALARGE AEROSOLS IN CALM AIR USING MANNIKINS , 1999 .

[30]  A. Maynard,et al.  A survey of wind speeds in indoor workplaces. , 1998, The Annals of occupational hygiene.

[31]  Clement Kleinstreuer,et al.  Dilute suspension flow with nanoparticle deposition in a representative nasal airway model , 2008 .

[32]  J. Tu,et al.  Deposition of Inhaled Wood Dust in the Nasal Cavity , 2007, Inhalation toxicology.

[33]  Ogden Tl,et al.  The human head as a dust sampler. , 1975, Inhaled particles.

[34]  William C. Hinds,et al.  Inhalability of large solid particles , 2002 .

[35]  W. S. Snyder,et al.  Report of the task group on reference man , 1979, Annals of the ICRP.