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Uncertainty in aspiration efficiency estimates from torso simplifications in computational fluid dynamics
Kimberly R Anderson1, T Renée Anthony
1Department of Occupational and Environmental Health, University of Iowa, 105 River Street, CPHB S333, Iowa City, IA 52242-5000, USA.
The Annals of Occupational Hygiene
|September 26, 2012
Summary
Computational fluid dynamics (CFD) studies on particle inhalation found that simplified human torso models do not significantly impact aspiration efficiency, despite differences in airflow simulation. This suggests less complex geometries are adequate for these analyses.
Area of Science:
- Fluid dynamics
- Aerosol science
- Biomedical engineering
Background:
- Computational fluid dynamics (CFD) is used to study particle inhalability, often employing simplified human torso models.
- Previous studies using truncated models underestimated upward air velocity, questioning their accuracy for aspiration estimation.
Purpose of the Study:
- To quantify errors from simplified geometries in CFD aspiration efficiency studies.
- To determine the necessary geometric detail for accurate human form representation in CFD.
Main Methods:
- Compared aspiration efficiencies for 7–116 µm particles using three torso models: simplified truncated cylinder, non-truncated cylinder, and realistic humanoid.
- Employed standard k-epsilon turbulence models and laminar particle trajectory simulations.
- Simulated freestream velocities (0.1–0.4 m/s) and breathing velocities (1.81–12.11 m/s).
Main Results:
- Significant differences in vertical velocity and critical area location were observed between the models.
- Despite geometric differences, aspiration efficiencies varied by less than 8.8% across all particle sizes and models.
Conclusions:
- Simplified human torso geometries in CFD studies introduce minimal error in aspiration efficiency calculations.
- Detailed geometric representation is not critical for accurately assessing particle aspiration efficiency.
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