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

Authors
Anderson-KR; Anthony-TR
Source
Ann Occup Hyg 2013 Mar; 57(2):184-199
NIOSHTIC No.
20043793
Abstract
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.
Keywords
Fluids; Hydrodynamics; Aerosols; Air-flow; Particle-aerodynamics; Humans; Anatomy; Analytical-models; Simulation-methods; Mathematical-models; Breathing; Inhalants; Anthropometry; Environmental-factors; Computer-models; Dust-inhalation; Dust-velocity; Dust-sampling; Author Keywords: aerosols; computational fluid dynamics; dust sampling conventions; inhalable dust
Contact
T. Renée Anthony, Department of Occupational and Environmental Health, University of Iowa, 105 River Street, CPHB S333, Iowa City, IA 52242-5000, USA
CODEN
AOHYA3
Publication Date
20130301
Document Type
Journal Article
Email Address
renee-anthony@uiowa.edu
Funding Type
Grant
Fiscal Year
2013
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-009290
Issue of Publication
2
ISSN
0003-4878
Source Name
Annals of Occupational Hygiene
State
IA
Performing Organization
University of Iowa
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