Aerosol particle transport and deposition in 
vertical and horizontal turbulent duct flows

Zhang, Haifeng; Ahmadi, Goodarz

doi:10.1017/s0022112099007284

Cited by 153 publications

(75 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Simulated deposition rates to the horizontal floor at two friction velocities from Zhang & Ahmadi (2000) are presented with the comparable experimental data of Sehmel (1973) in Figure 2.46. The primary deposition mechanism in this case is gravitational settling and excellent agreement between the simulations and the experiments is observed.…”

Section: 56b Lagrangian Simulations With Turbulent Flow From Les mentioning

confidence: 95%

“…2.46 Deposition to a smooth horizontal floor in the DNS-Lagrangian simulation of Zhang and Ahmadi (2000) at two friction velocities compared to the similar experiments of Sehmel (1973). 3.15 Comparison of dimensionless ceiling deposition velocities measured at three air speeds in the steel system with the data of Sehmel (1973).…”

Section: Table Of Contentsmentioning

confidence: 99%

“…2.44 Deposition to a smooth vertical wall in the DNS-Lagrangian simulation of Zhang & Ahmadi (2000) with downward and horizontal flow at low xviii friction velocities compared to the experiments of Liu & Agarwal (1974). 182…”

Section: Table Of Contentsmentioning

confidence: 99%

See 2 more Smart Citations

Particle deposition in ventilation ducts

Sippola¹

2002

View full text Add to dashboard Cite

Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation.Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence exposures to particles indoors, diminish HVAC performance and lead to secondary pollutant release within buildings. This dissertation advances the understanding of particle behavior in HVAC systems and the fates of indoor particles by means of experiments and modeling.Laboratory experiments were conducted to quantify particle deposition rates in horizontal ventilation ducts using real HVAC materials. Particle deposition experiments were conducted in steel and internally insulated ducts at air speeds typically found in ventilation ducts, 2-9 m/s. Behaviors of monodisperse particles with diameters in the size range 1-16 µm were investigated. Deposition rates were measured in straight ducts with 1 2 a fully developed turbulent flow profile, straight ducts with a developing turbulent flow profile, in duct bends and at S-connector pieces located at duct junctions. In straight ducts with fully developed turbulence, experiments showed deposition rates to be highest at duct floors, intermediate at duct walls, and lowest at duct ceilings. Deposition rates to a given surface increased with an increase in particle size or air speed. Deposition was much higher in internally insulated ducts than in uninsulated steel ducts. In most cases, deposition in straight ducts with developing turbulence, in duct bends and at S-connectors at duct junctions was higher than in straight ducts with fully developed turbulence.Measured deposition rates were generally higher than predicted by published models.A model incorporating empirical equations based on the experimental measurements was applied to evaluate particle losses in supply and return duct runs. Model results suggest that duct losses are negligible for particle sizes less than 1 µm and complete for particle sizes greater than 50 µm. Deposition to insulated ducts, horizontal duct floors and bends are predicted to control losses in duct systems. When combined with models for HVAC filtration and deposition to indoor surfaces to predict the ultimate fates of particles within buildings, these results suggest that ventilation ducts play only a small role in determining indoor particle concentrations, especially when HVAC filtration is present.However, the measured and modeled particle deposition rates are expected to be important for ventilation system contamination. ChairDate

show abstract

Section: 56b Lagrangian Simulations With Turbulent Flow From Les mentioning

confidence: 95%

Section: Table Of Contentsmentioning

confidence: 99%

See 1 more Smart Citation

Particle deposition in ventilation ducts

Sippola¹

2002

View full text Add to dashboard Cite

show abstract

“…Zhang and Ahmadi (2000) successfully applied such scheme in simulating particle deposition in channel flows.…”

Section: Calculation Of the Particle Deposition Velocity From Lagrangmentioning

confidence: 99%

Prediction of particle deposition onto indoor surfaces by CFD with a modified Lagrangian method

Zhang¹,

Chen²

2009

Atmospheric Environment

166

View full text Add to dashboard Cite

Accurate prediction of particle deposition indoors is important to estimate exposure risk of building occupants to particulate matter. The prediction requires accurate modeling of airflow, turbulence, and interactions between particles and eddies close to indoor surfaces. This study used a 2 ′ − v f turbulence model with a modified Lagrangian method to predict the particle deposition in enclosed environments. The 2 ′ − v f model can accurately calculate the normal turbulence fluctuation 2 ′ v , which mainly represents the anisotropy of turbulence near walls.Based on the predicted 2 ′ v , we proposed an anisotropic particle-eddy interaction model for the prediction of particle deposition by the Lagrangian method. The model performance was assessed by comparing the computed particle deposition onto differently oriented surfaces with the experimental data in a turbulent channel flow and in a naturally convected cavity available from the literature. The predicted particle deposition velocities agreed reasonably with the experimental data for different sizes of particles ranging from 0.01μm to 50μm in diameter. This study concluded that the Lagrangian method can predict indoor particle deposition with reasonable accuracy provided the near-wall turbulence and its interactions with particles are correctly modeled.

show abstract

“…Such information is needed to provide insight in the micromechanism of particle removal (Zhang and Ahmadi 2000). This work presents an experimental investigation of the conditions under which a transient fluid flow causes spherical glass microparticles to detach from different surfaces.…”

Section: Introductionmentioning

confidence: 99%

High Resolution Study of Micrometer Particle Detachment on Different Surfaces

Kassab

Ugaz

King

et al. 2013

Aerosol Science and Technology

View full text Add to dashboard Cite

In an effort to identify particle initial motion prior liftoff interactions of micrometer glass beads (10-100 µm) on glass, ceramic, and hardwood substrates were investigated experimentally. Particles were deposited on the lower surface of a 10 cm 2 wind tunnel by gravitational settling. Air flows were imposed from an open entrance at average velocities up to 16 m/s. Individual particle trajectories obtained by high-speed imaging reveal three different types of motion: rolling/bouncing (saltation caused by the movement of hard particles over an uneven surface in a turbulent flow of air), immediate liftoff (particles completely leave the surface with no or minimal initial rolling/bouncing) and complex motion (particles travel with rolling/bouncing motion on the surface for a certain distance before final liftoff). Surface roughness significantly affects the particle initial motion prior to liftoff. The majority of particle trajectories from the glass substrate were parallel to the surface with complex motion. Hardwood substrates took the longest time for initial particle movement (t >1 s) causing a more rapid liftoff. The ceramic substrate showed the most rolling/bouncing motion, for 80% of the particles. The detachment percentage initially follows an exponentially increasing trend for a period of ∼1 s, followed by a plateau phase for a period of 5 s. Changing the velocity, substrate, and particle size significantly affects particle detachment. Incorporating the different types of particle motion prior to liftoff into detachment mode models, and understanding how their relative contributions change with different particle and substrate materials, can potentially yield improved predictive capabilities.

show abstract

Aerosol particle transport and deposition in vertical and horizontal turbulent duct flows

Cited by 153 publications

References 28 publications

Particle deposition in ventilation ducts

Particle deposition in ventilation ducts

Prediction of particle deposition onto indoor surfaces by CFD with a modified Lagrangian method

High Resolution Study of Micrometer Particle Detachment on Different Surfaces

Contact Info

Product

Resources

About