Uncertainty in aspiration efficiency estimates from torso simplifications in computational fluid dynamics simulations

Details

• Personal Author:
  Anderson KR ; Anthony, T. Renée
• Description:
  Computational fluid dynamics (CFD) has been used to report particle inhalability in low velocity freestreams, where realistic faces but simplified, truncated, and cylindrical human torsos were used. When compared to wind tunnel velocity studies, the truncated models were found to underestimate the air's upward velocity near the humans, raising questions about aspiration estimation. This work compares aspiration efficiencies for particles ranging from 7 to 116 µm using three torso geometries: (i) a simplified truncated cylinder, (ii) a non-truncated cylinder, and (iii) an anthropometrically realistic humanoid body. The primary aim of this work is to (i) quantify the errors introduced by using a simplified geometry and (ii) determine the required level of detail to adequately represent a human form in CFD studies of aspiration efficiency. Fluid simulations used the standard k-epsilon turbulence models, with freestream velocities at 0.1, 0.2, and 0.4 m s(-1) and breathing velocities at 1.81 and 12.11 m s(-1) to represent at-rest and heavy breathing rates, respectively. Laminar particle trajectory simulations were used to determine the upstream area, also known as the critical area, where particles would be inhaled. These areas were used to compute aspiration efficiencies for facing the wind. Significant differences were found in both vertical velocity estimates and the location of the critical area between the three models. However, differences in aspiration efficiencies between the three forms were <8.8% over all particle sizes, indicating that there is little difference in aspiration efficiency between torso models. [Description provided by NIOSH]
• Subjects:
  Aerosols Air Movements Anatomy Dust Environmental Health Inhalation Exposure Occupational Health Particulate Matter Respiratory System Safety Software

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• Keywords:
  Air-flow Analytical-models Anthropometry Author Keywords: Aerosols Breathing Computational Fluid Dynamics Computer-models Dust-inhalation Dust-sampling Dust-velocity Dust Sampling Conventions Environmental-factors Fluids Humans Hydrodynamics Inhalable Dust Inhalants Mathematical-models Particle-aerodynamics Simulation-methods

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• ISSN:
  0003-4878
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Iowa ; OSHA Region 7
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  184-199
• Volume:
  57
• Issue:
  2
• NIOSHTIC Number:
  nn:20043793
• Citation:
  Ann Occup Hyg 2013 Mar; 57(2):184-199
• Contact Point Address:
  T. Renée Anthony, Department of Occupational and Environmental Health, University of Iowa, 105 River Street, CPHB S333, Iowa City, IA 52242-5000, USA
• Email:
  renee-anthony@uiowa.edu
• Federal Fiscal Year:
  2013
• Performing Organization:
  University of Iowa
• Peer Reviewed:
  True
• Start Date:
  20080601
• Source Full Name:
  Annals of Occupational Hygiene
• End Date:
  20130531
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:596436a3010e180f374d440b7adebc4414e8e0527217c36d6a3d6123e0259e0aa1b8388dab551337b2a47db0e740c966f3dad3d2e26d7e984cb60886e0a74f66
• Download URL:
  https://stacks.cdc.gov/view/cdc/199688/cdc_199688_DS1.pdf
• File Type:
  [PDF - 967.98 KB ]