Experimental Studies on Dispersion of Fine Non-Spherical Particles in Enclosed Spaces

2013 ◽  
Vol 310 ◽  
pp. 3-6 ◽  
Author(s):  
Zi Biao Song ◽  
Xiao Lu Wu ◽  
Yu Qian Ye ◽  
Chang Jun Rong
Keyword(s):  
Fine Particle ◽  
Indoor Environment ◽  
Carbon Nanofiber ◽  
Dispersion Model ◽  
Experimental Studies ◽  
Particle Dispersion ◽  
Spherical Particles ◽  
Dispersion Process ◽  
Aerosol Dispersion ◽  
Mass Concentrations

Study on the fine particle dispersion in the room is very important for creating and maintaining a healthy indoor environment. An experiment of a carbon nanofiber material blown in smoke box was taken and the mass concentrations of the aerosol formed by this material were measured. Dispersion process of this material in the smoke box was simulated by random walk model, spherical particles aerosol dispersion model and non-spherical particles aerosol dispersion model, respectively. The setting velocities of the aerosol in the smoke box were calculated according to the mass concentrations at different times and the influences of gravity and non-spherical particles’ shape on its dispersion process were analyzed in theory.

Mathematical Model Studies on Dispersion of Fine Non-Spherical Particles in Enclosed Spaces

2013 ◽  
Vol 756-759 ◽  
pp. 4699-4702
Author(s):  
Zi Biao Song ◽  
Chun Ge ◽  
Shu Xiong Zhang ◽  
Xiao Lu Wu
Keyword(s):  
Fine Particle ◽  
Indoor Environment ◽  
Dispersion Model ◽  
Random Force ◽  
Particle Dispersion ◽  
Spherical Particles ◽  
Theory Analysis ◽  
Dispersion Process ◽  
Model Studies ◽  
Better Than

Study on the fine particle dispersion in the room is very important for creating and maintaining a healthy indoor environment. The paper presented a new dispersion model of fine non-spherical particles formulated in a Lagrangian way based on its dynamic characteristics. In this model, the effects of gravity, resistance, particles shape and random force were taken into account. The influences of gravity and non-spherical particles shape on its dispersion process were analyzed in theory. Simulation result and theory analysis showed the models established in the paper performed better than the random walk model.

Experimental Study on Modified Model of Indoor Bio-Aerosol Dispersion

2011 ◽  
Vol 383-390 ◽  
pp. 6548-6553
Author(s):  
Yan Ding ◽  
Zhe Tian ◽  
Neng Zhu
Keyword(s):  
Indoor Environment ◽  
Control Method ◽  
Dispersion Model ◽  
Transmission Route ◽  
Modified Model ◽  
Office Environment ◽  
Air Supply ◽  
Continuous Point ◽  
Aerosol Dispersion ◽  
Supply Pattern

The main transmission route of infectious disease is the dispersion of exhaled particulate matter with pathogen attached on. Therefore, the exploration on the dispersion routine of bio-aerosol is a significant approach for researching control method of indoor infection. Based on the continuous point-source dispersion model, this article puts forward corresponding modified methods according to different airflow patterns and make it become a reasonable predicting tool for the dispersion of bio-aerosol in indoor environment. Such predicting tool is also validated by a bacteria emanating experiment whose results show a notable improvement on predicting accuracy of the modified model. Additionally, the experiment results also indicate that the under floor air supply pattern embraces preferable controlling ability on indoor infections for each occupant in an office environment.

The Analysis of the Impact of Particles on Cavitation Flow Development

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
Boštjan Gregorc ◽  
Matjaž Hriberšek ◽  
Andrej Predin
Keyword(s):  
Dispersion Model ◽  
Phase Particle ◽  
Experimental Studies ◽  
Particle Dispersion ◽  
Solid Particles ◽  
Cavitation Flow ◽  
Flow Conditions ◽  
Cavitation Tunnel ◽  
The Impact ◽  
Additional Phase

The purpose of this paper is to present an analysis of the impact of solid particles on the development of cavitation flow conditions around a hydrofoil. Experimental studies were conducted in a cavitation tunnel with different mixtures of particles and water. The effect of the particles on the development of cavitation flows was modeled by using an additional phase particle dispersion model (Euler-Euler). Numerical modeling was performed using the CFD software. The impact on the cavity model with the parametric analysis of the entry conditions of particles in the calculation domain was investigated, with a focus on the solid shear viscosity. Another purpose of this research was to present the possibility of modeling the development of the vapor phase in the commercial CFD software package, while taking into account the impact of particles. This paper presents the results of the experimental measurements and their comparison with numerical simulations.

scholarly journals Ship emissions measurement in the Arctic from plume intercepts of the Canadian Coast Guard <i>Amundsen</i> icebreaker from the <i>Polar 6</i> aircraft platform

2016 ◽  
Author(s):  
A. A. Aliabadi ◽  
J. L. Thomas ◽  
A. Herber ◽  
R. M. Staebler ◽  
W. R. Leaitch ◽  
...  
Keyword(s):  
Emission Factor ◽  
Dispersion Model ◽  
Experimental Studies ◽  
Emission Factors ◽  
Particle Dispersion ◽  
Coast Guard ◽  
The Arctic ◽  
Plume Dispersion ◽  
Ship Emissions ◽  
Ship Traffic

Abstract. Decreasing sea ice and increasing marine navigability in northern latitudes have changed Arctic ship traffic patterns in recent years and are predicted to increase annual ship traffic in the Arctic in the future. Development of effective regulations to manage environmental impacts of shipping requires an understanding of ship emissions and atmospheric processing in the Arctic environment. As part of the summer 2014 NETCARE (Network on Climate and Aerosols) campaign, the plume dispersion and gas and particle emission factors of emissions originating from the Canadian Coast Guard Amundsen icebreaker operating near Resolute Bay, NU, Canada have been investigated. The Amundsen burnt distillate fuel with 1.5 wt % sulfur. Emissions were studied via plume intercepts using aircraft measurements, an analytical plume dispersion model, and using the FLEXPART-WRF Lagrangian particle dispersion model. The first plume intercepts by research aircraft were carried out on 19 July 2014 during the operation of the Amundsen in the open water. The second and third plume intercept measurements were carried out on 20 and 21 July 2014 when the Amundsen had reached the ice edge and operated under icebreaking conditions. Typical of Arctic marine navigation, the engine load was low compared to cruising conditions for all of the plume intercepts. The measured species included mixing ratios of CO2, NOx, CO, SO2, particle number concentration (CN), refractory Black Carbon (rBC), and Cloud Condensation Nuclei (CCN). The results were compared to similar experimental studies in mid latitudes. Plume expansion rates (γ) were calculated using the analytical model and found to be γ = 0.75 ± 0.80, 0.93 ± 0.37, and 1.19 ± 0.39 for plumes 1, 2, and 3, respectively. These rates are smaller than prior studies conducted at mid latitudes, likely due to polar boundary layer dynamics, including reduced turbulent mixing compared to mid latitudes. All emission factors were in agreement with prior observations at low engine loads in mid latitudes. Icebreaking increased the NOx emission factor from EFNOx = 22.3 ± 8.0 to 57.8 ± 11.0 and 65.8 ± 4.0 g kg–diesel−1 for plumes 1, 2, and 3, likely due to change in combustion temperatures. The CO emission factor was EFCO = 6.4 ± 11.7, 6.8 ± 2.2 and 5.0 ± 1.0 g kg–diesel−1 for plumes 1, 2, and 3. The rBC emission factor was EFrBC = 0.20 ± 0.04 and 0.25 ± 0.12 g kg–diesel−1 for plumes 1 and 2. The CN emission factor was reduced while icebreaking from EFCPC = 1.96 ± 0.41 to 0.43 ± 0.11 and 0.47 ± 0.04 × 1016 kg–diesel−1 for plumes 1, 2, and 3. At 0.6 % supersaturation, the CCN emission factor was lower than observations in mid latitudes at low engine loads with EFCCN = 1.63 ± 0.41 to 1.06 ± 0.32 and 0.28 ± 0.07 × 1014 kg–diesel−1 for plumes 1, 2, and 3.

scholarly journals Ship emissions measurement in the Arctic by plume intercepts of the Canadian Coast Guard icebreaker <i>Amundsen</i> from the <i>Polar 6</i> aircraft platform

2016 ◽  
Vol 16 (12) ◽  
pp. 7899-7916 ◽  
Author(s):  
Amir A. Aliabadi ◽  
Jennie L. Thomas ◽  
Andreas B. Herber ◽  
Ralf M. Staebler ◽  
W. Richard Leaitch ◽  
...  
Keyword(s):  
Emission Factor ◽  
Dispersion Model ◽  
Experimental Studies ◽  
Emission Factors ◽  
Particle Dispersion ◽  
Coast Guard ◽  
The Arctic ◽  
Plume Dispersion ◽  
Ship Emissions ◽  
Ship Traffic

Abstract. Decreasing sea ice and increasing marine navigability in northern latitudes have changed Arctic ship traffic patterns in recent years and are predicted to increase annual ship traffic in the Arctic in the future. Development of effective regulations to manage environmental impacts of shipping requires an understanding of ship emissions and atmospheric processing in the Arctic environment. As part of the summer 2014 NETCARE (Network on Climate and Aerosols) campaign, the plume dispersion and gas and particle emission factors of effluents originating from the Canadian Coast Guard icebreaker Amundsen operating near Resolute Bay, NU, Canada, were investigated. The Amundsen burned distillate fuel with 1.5 wt % sulfur. Emissions were studied via plume intercepts using the Polar 6 aircraft measurements, an analytical plume dispersion model, and using the FLEXPART-WRF Lagrangian particle dispersion model. The first plume intercept by the research aircraft was carried out on 19 July 2014 during the operation of the Amundsen in the open water. The second and third plume intercepts were carried out on 20 and 21 July 2014 when the Amundsen had reached the ice edge and operated under ice-breaking conditions. Typical of Arctic marine navigation, the engine load was low compared to cruising conditions for all of the plume intercepts. The measured species included mixing ratios of CO2, NOx, CO, SO2, particle number concentration (CN), refractory black carbon (rBC), and cloud condensation nuclei (CCN). The results were compared to similar experimental studies in mid-latitudes. Plume expansion rates (γ) were calculated using the analytical model and found to be γ  =  0.75 ± 0.81, 0.93 ± 0.37, and 1.19 ± 0.39 for plumes 1, 2, and 3, respectively. These rates were smaller than prior studies conducted at mid-latitudes, likely due to polar boundary layer dynamics, including reduced turbulent mixing compared to mid-latitudes. All emission factors were in agreement with prior observations at low engine loads in mid-latitudes. Ice-breaking increased the NOx emission factor from EFNOx  =  43.1 ± 15.2 to 71.6 ± 9.68 and 71.4 ± 4.14 g kg-diesel−1 for plumes 1, 2, and 3, likely due to changes in combustion temperatures. The CO emission factor was EFCO  =  137 ± 120, 12.5 ± 3.70 and 8.13 ± 1.34 g kg-diesel−1 for plumes 1, 2, and 3. The rBC emission factor was EFrBC  =  0.202 ± 0.052 and 0.202 ± 0.125 g kg-diesel−1 for plumes 1 and 2. The CN emission factor was reduced while ice-breaking from EFCN  =  2.41 ± 0.47 to 0.45 ± 0.082 and 0.507 ± 0.037  ×  1016 kg-diesel−1 for plumes 1, 2, and 3. At 0.6 % supersaturation, the CCN emission factor was comparable to observations in mid-latitudes at low engine loads with EFCCN  =  3.03 ± 0.933, 1.39 ± 0.319, and 0.650 ± 0.136  ×  1014 kg-diesel−1 for plumes 1, 2, and 3.

Experimental Study on the Effects of Radial Dispersion of Spherical Particles on the Suspension Rheology

2019 ◽  
Author(s):  
Misa Kawaguchi ◽  
Tomohiro Fukui ◽  
Kenichi Funamoto ◽  
Suguru Miyauchi ◽  
Toshiyuki Hayase
Keyword(s):  
Experimental Studies ◽  
Circular Cross Section ◽  
Inertial Force ◽  
Suspended Particles ◽  
Particle Dispersion ◽  
Spherical Particles ◽  
Suspension Flow ◽  
Radial Dispersion ◽  
Flow Through ◽  
The Difference

Abstract Experimental studies were performed to characterize the effects of the microstructure on the rheology of suspension. We focused on the change in the dispersion of the suspended particles under different particle Reynolds number conditions. Suspension flow through a microchannel with a circular cross-section was measured, and the radial dispersion of suspended particles and the velocity profiles were obtained. It was suggested that the particle dispersion could be changed owing to the difference in inertial force acting on the particles.

scholarly journals Large-Scale Atmospheric Dispersal Simulations Identify Likely Airborne Incursion Routes of Wheat Stem Rust Into Ethiopia

2017 ◽  
Vol 107 (10) ◽  
pp. 1175-1186 ◽  
Author(s):  
M. Meyer ◽  
L. Burgin ◽  
M. C. Hort ◽  
D. P. Hodson ◽  
C. A. Gilligan
Keyword(s):  
Stem Rust ◽  
Large Scale ◽  
Dispersion Model ◽  
Fungal Spores ◽  
Disease Outbreaks ◽  
Particle Dispersion ◽  
East African ◽  
Wheat Stem Rust ◽  
Sub Saharan ◽  
African Rift

In recent years, severe wheat stem rust epidemics hit Ethiopia, sub-Saharan Africa’s largest wheat-producing country. These were caused by race TKTTF (Digalu race) of the pathogen Puccinia graminis f. sp. tritici, which, in Ethiopia, was first detected at the beginning of August 2012. We use the incursion of this new pathogen race as a case study to determine likely airborne origins of fungal spores on regional and continental scales by means of a Lagrangian particle dispersion model (LPDM). Two different techniques, LPDM simulations forward and backward in time, are compared. The effects of release altitudes in time-backward simulations and P. graminis f. sp. tritici urediniospore viability functions in time-forward simulations are analyzed. Results suggest Yemen as the most likely origin but, also, point to other possible sources in the Middle East and the East African Rift Valley. This is plausible in light of available field surveys and phylogenetic data on TKTTF isolates from Ethiopia and other countries. Independent of the case involving TKTTF, we assess long-term dispersal trends (>10 years) to obtain quantitative estimates of the risk of exotic P. graminis f. sp. tritici spore transport (of any race) into Ethiopia for different ‘what-if’ scenarios of disease outbreaks in potential source countries in different months of the wheat season.

scholarly journals Atmospheric rivers moisture sources from a Lagrangian perspective

2016 ◽  
Vol 7 (2) ◽  
pp. 371-384 ◽  
Author(s):  
Alexandre M. Ramos ◽  
Raquel Nieto ◽  
Ricardo Tomé ◽  
Luis Gimeno ◽  
Ricardo M. Trigo ◽  
...  
Keyword(s):  
North Atlantic ◽  
Dispersion Model ◽  
Local Maximum ◽  
Detection Algorithm ◽  
Ocean Basin ◽  
Particle Dispersion ◽  
Western Coast ◽  
Moisture Uptake ◽  
Lagrangian Analysis ◽  
Data Set

Abstract. An automated atmospheric river (AR) detection algorithm is used for the North Atlantic Ocean basin, allowing the identification of the major ARs affecting western European coasts between 1979 and 2012 over the winter half-year (October to March). The entire western coast of Europe was divided into five domains, namely the Iberian Peninsula (9.75° W, 36–43.75° N), France (4.5° W, 43.75–50° N), UK (4.5° W, 50–59° N), southern Scandinavia and the Netherlands (5.25° E, 50–59° N), and northern Scandinavia (5.25° E, 59–70° N). Following the identification of the main ARs that made landfall in western Europe, a Lagrangian analysis was then applied in order to identify the main areas where the moisture uptake was anomalous and contributed to the ARs reaching each domain. The Lagrangian data set used was obtained from the FLEXPART (FLEXible PARTicle dispersion) model global simulation from 1979 to 2012 and was forced by ERA-Interim reanalysis on a 1° latitude–longitude grid. The results show that, in general, for all regions considered, the major climatological areas for the anomalous moisture uptake extend along the subtropical North Atlantic, from the Florida Peninsula (northward of 20° N) to each sink region, with the nearest coast to each sink region always appearing as a local maximum. In addition, during AR events the Atlantic subtropical source is reinforced and displaced, with a slight northward movement of the sources found when the sink region is positioned at higher latitudes. In conclusion, the results confirm not only the anomalous advection of moisture linked to ARs from subtropical ocean areas but also the existence of a tropical source, together with midlatitude anomaly sources at some locations closer to AR landfalls.

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