Computational fluid dynamics investigation of particle inhalability

Anthony, T; Flynn, Michael R.

doi:10.1016/j.jaerosci.2005.06.009

Cited by 47 publications

(57 citation statements)

References 21 publications

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“…A more reasonable approach is to compare the particle aspiration efficiency of the simulated PHISH sampler to that of a human that has matched orientation in lowvelocity freestream conditions. For this, two data sets were available to compare our simulated sampler performance: mannequin studies of solid particles (Kennedy and Hinds, 2002) and CFD humanoid simulations of liquid and solid particles (Anthony and Flynn, 2006b). Both of these studies examined particle aspiration efficiencies over the same range of particle sizes, and both used a breathing human surrogate facing the wind at low indoor air velocity of 0.4 m s −1 .…”

Section: Discussionmentioning

confidence: 99%

“…5a,b illustrates the aspiration efficiencies of Table 4 along with human aspiration efficiency data for similar 0.4 m s −1 freestream studies for the 0° and 30° down PHISH orientations, respectively. The gray band provides the aspiration efficiency curve generated in previous CFD simulations of human aspiration at moderate mouth-breathing velocity and 0.4 m s −1 freestream velocity for the same forward-facing orientation (Anthony and Flynn, 2006b): the bottom of the band represents the no-bounce particle aspiration and the top of the band represents aspiration that includes particle bounce on the human face. The previous study examined aspiration of particles into a continuously inhaling mouth, where the human head had realistic facial details (nose, lips, chin, neck, etc.)…”

Section: Discussionmentioning

confidence: 99%

“…The release coordinates for the particles that were aspirated were used to compute the critical area (A c ) defined as the upstream area that encompassed all particles that were aspirated into the sampler. Equation (8) was used to compute the aspiration efficiency of the sampler at the given orientation (Anthony and Flynn, 2006b). Four conditions of bounce were evaluated to examine the effect of aerosol type on the sampler's efficiency.…”

Section: Particle Simulationsmentioning

confidence: 99%

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Design and Computational Fluid Dynamics Investigation of a Personal, High Flow Inhalable Sampler

Anthony

Landázuri

Dyke

et al. 2010

The Annals of Occupational Hygiene

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The objective of this research was to develop an inlet to meet the inhalable sampling criterion at 10 l min −1 flow using the standard, 37-mm cassette. We designed a porous head for this cassette and evaluated its performance using computational fluid dynamics (CFD) modeling. Particle aspiration efficiency was simulated in a wind tunnel environment at 0.4 m s −1 freestream velocity for a facing-the-wind orientation, with sampler oriented at both 0° (horizontal) and 30° down angles. The porous high-flow sampler oriented 30° downward showed reasonable agreement with published mannequin wind tunnel studies and humanoid CFD investigations for solid particle aspiration into the mouth, whereas the horizontal orientation resulted in oversampling. Liquid particles were under-aspirated in all cases, however, with 41-84% lower aspiration efficiencies relative to solid particles. A sampler with a single central 15-mm pore at 10 l min −1 was also investigated and was found to match the porous sampler's aspiration efficiency for solid particles; the single-pore sampler is expected to be more suitable for liquid particle use.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Particle Simulationsmentioning

confidence: 99%

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Design and Computational Fluid Dynamics Investigation of a Personal, High Flow Inhalable Sampler

Anthony

Landázuri

Dyke

et al. 2010

The Annals of Occupational Hygiene

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“…They could not resolve the effects of velocity differences between simulation and experimental data by repositioning the simulated particle source within 5 mm of the matched experimental position, indicating that torso simplification resulted in velocity differences sufficient to shift the critical upstream aspiration area. In later full-scale human simulations, Anthony and Flynn (2006b) compared computational aspiration efficiencies to facing-the-wind experimental data from Kennedy and Hinds (2002). Particles smaller than 52 µm compared well with the experimental results from Kennedy and Hinds (2002), but for particles larger than 52 µm the CFD model underestimates aspiration efficiencies compared to published results.…”

Section: Introductionmentioning

confidence: 92%

Uncertainty in Aspiration Efficiency Estimates from Torso Simplifications in Computational Fluid Dynamics Simulations

Anderson

Anthony

2012

The Annals of Occupational Hygiene

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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.

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“…To determine this radius, we reviewed an earlier experimental study of Kennedy and Hinds (2002) . This is between the values of S i = 0.0001386 m 2 used in the digital head model of Anthony and Flynn (2005) and S i = 0.00016 m 2 used for the mouth area in manikin-based experiments of Kennedy and Hinds (2002). This configuration is analogous to a spherical aerosol sampler that has a radius of R h = 0.09 m and a point-like opening of R i = 0.007 m.…”

Section: Selection Of Parameters and Model Validationmentioning

confidence: 92%

Assessing the Protection Provided by Facepiece Filtering Respirator: New Model Involving Spherical Porous Layer with Annular Peripheral Opening

Mukhametzanov

Grinshpun

Zaripov

et al. 2016

Aerosol Air Qual. Res.

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The penetration of aerosol particles inside a facepiece filtering respirator (FFR) was investigated using a novel model, which involved a spherical porous layer representing a filter and an annular peripheral opening representing a faceseal leakage. The model utilized a two-dimensional laminar incompressible flow in a free space and porous zones that are numerically solved by a computational fluid dynamic code FLUENT. Following the model validation, the efficiency of an FFR with an annular faceseal leakage opening was investigated as a function of the inhalation flow rate, particle size, and the ratio of the leak-to-filter areas. The filter material permeability was determined for a conventional N95 filter medium. It was found -for two inhalation flow rates (Q i = 30 and 85 L min -1 ) and three particle diameters (d p = 50 nm, 100 nm and 1 µm) -that once the faceseal leakage area exceeded 0.1% of the total surface of an N95 facepiece, the respirator was unable to offer the 95% protection -the minimum level that should be provided by its filter. It was demonstrated that under certain leakage condition (partially determined by the inhalation flow rate), the respirator protection level becomes independent on the particle size; furthermore, it is not anymore affected by the efficiency of its filter, and is only influenced by the size of the faceseal leakage.

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Computational fluid dynamics investigation of particle inhalability

Cited by 47 publications

References 21 publications

Design and Computational Fluid Dynamics Investigation of a Personal, High Flow Inhalable Sampler

Design and Computational Fluid Dynamics Investigation of a Personal, High Flow Inhalable Sampler

Uncertainty in Aspiration Efficiency Estimates from Torso Simplifications in Computational Fluid Dynamics Simulations

Assessing the Protection Provided by Facepiece Filtering Respirator: New Model Involving Spherical Porous Layer with Annular Peripheral Opening

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