Journal articles on the topic 'Particle deposition'
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1
Tan, Kun. "Numerical Study on Simulating the Deposition Process of Cold Spray Multi-Particle Al-6061 based on CEL Method." Mechanics and Advanced Technologies 8, no. 1(100) (March 19, 2024): 23–29. http://dx.doi.org/10.20535/2521-1943.2024.8.1(100).295144.
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Cold spray is a solid-state deposition technique that improves the performance of part surfaces. Most scholars use the CEL framework to simulate the deposition of single particles on the substrate; Single particle depositions cannot fully characterize coating conditions. This article proposes to use the CEL method to simulate the deposition process of cold spray multi-particles on the Al6061 substrate. A multi-particle wrapped model is nested in a deposition model created by CEL to simulate the cold spray multi-particle deposition process. The Euler-Lagrangian method has the characteristics of high accuracy and robustness, and was selected as the method for multi-particle deposition model simulation; The CEL framework is a feasible method to simulate the actual cold spray multi-particle deposition process. The results show that the CEL framework can simulate the deposition of cold sprayed Al6061 multi-particles on the Al6061 substrate, observe the EVF Void value of the coating, and monitor the porosity of the coating after deposition. It is observed that the maximum substrate surface temperature after deposition is 528.2K and is located at the junction of particle and particle impact; By analyzing the temperature change curve of five points collected on the substrate over time, the curve appears multiple inflection points, indicating that heat transfer occurs between the particles and the substrate during the deposition process; the substrate first heats up and then cools down. During the multi-deposition process, the particles undergo plastic deformation and continuously squeeze the coating, thereby achieving interconnection between the particles and the substrate; Mechanical interlocking between particles forms a coating.
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Phuong, Nguyen Lu, Nguyen Dang Khoa, and Kazuhide Ito. "Comparative numerical simulation of inhaled particle dispersion in upper human airway to analyse intersubject differences." Indoor and Built Environment 29, no. 6 (January 8, 2020): 793–809. http://dx.doi.org/10.1177/1420326x19894128.
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This study predicted the total and regional deposition of particles in realistic upper human airways and demonstrated the effects of intersubject variations in deposition fraction. Two airway models were studied under flow rates ranging from 0.45 to 2.4 m3/h and particle aerodynamic diameters from 1 to 10 μm. The total deposition predictions were validated using in vivo and in vitro experimental data. The intricate airway structures generated heterogeneities of airflow distributions and corresponding particle dispersions and depositions in the models. Nevertheless, with modified inertial parameters, the total deposition fraction curves of the two human upper airway models, as functions of flow rates, converged to a single function. However, regional particle deposition fractions differed significantly among the two models. The surface pressure and wall-shear stress distribution were investigated to assess the relationship of surface pressure and wall-shear stress with hotspot locations in upper airways of both models. For one subject (model A), the central nasal passage regions were found to be sites of higher deposition over the range of particle sizes and flow rates targeted in this study. For the other subject (model B), higher deposition was mostly observed in the vestibule region, caused due to particle inertia as the airway consisted of curvatures. The accelerated flow regions acted as a natural filter to high inertial particles. The results indicated that both total and regional depositions exhibited significant intersubject differences.
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Li, Debo, Qisheng Xu, Yaming Liu, Yin Libao, and Jin Jun. "Numerical Simulation of Particles Deposition in a Human Upper Airway." Advances in Mechanical Engineering 6 (January 1, 2014): 207938. http://dx.doi.org/10.1155/2014/207938.
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Based on the CT scanned images, a realistic geometric model from nasal cavity to upper six-generation bronchia is rebuilt. In order to effectively simulate the particle movement and deposition, LES model is used and the particles are tracked in the frame of Lagrange. Seven kinds of typical particles, including micron particles (1, 5, and 10 μm) and nanoparticles (1, 5, 20, and 100 nm), and three representative respiratory intensities are adopted as computational case, respectively. Deposition efficiency ( D E), deposition concentration ( D C), and capture efficiency ( C E) are introduced. Furthermore, the locations of particle deposition are visualized. The results indicate that the injecting particles from different nasal inlet present “transposition effect.”The D E values of micron particles are much higher than nanoparticles. The particle diameter plays a weaker role in nanoparticle depositions than micron particles. The highest values of D E and D C both occur in nasal cavity, while the highest C E up to 99.5% occurs in bronchus region.
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Lu, Hao, and Li-zhi Zhang. "Particle Deposition Characteristics and Efficiency in Duct Air Flow over a Backward-Facing Step: Analysis of Influencing Factors." Sustainability 11, no. 3 (January 31, 2019): 751. http://dx.doi.org/10.3390/su11030751.
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Dry deposition of airborne particles in duct air flow over a backward-facing step (BFS) is commonly encountered in built environments and energy engineering. However, the understanding of particle deposition characteristics in BFS flow remains insufficient. Thus, this study investigated particle deposition behaviors and efficiency in BFS flow by using the Reynolds stress model and the discrete particle model. The influences of flow velocities, particle diameters, and duct expansion ratios on particle deposition characteristics were examined and analyzed. After numerical validation, particle deposition velocities, deposition efficiency, and deposition mechanisms in BFS duct flow were investigated in detail. The results showed that deposition velocity in BFS duct flow monotonically increases when particle diameter increases. Moreover, deposition velocity falls with increasing expansion ratio but rises with increasing air velocity. Deposition efficiency, the ratio of deposition velocity, and flow drag in a BFS duct is higher for small particles but lower for large particles as compared with a uniform duct. A higher particle deposition efficiency can be achieved by BFS with a smaller expansion ratio. The peak deposition efficiency can reach 33.6 times higher for 1-μm particles when the BFS expansion ratio is 4:3. Moreover, the “particle free zone” occurs for 50-μm particles in the BFS duct and is enlarged when the duct expansion ratio increases.
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Li, Yuan, and Yue Qiu. "Co-Deposition of Binary Particles during Slip Casting Process." Advanced Materials Research 189-193 (February 2011): 2917–20. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.2917.
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Co-deposition of silicon carbide particles and carbon (or carbon sources) particles is essential for preparation of reaction bonded silicon carbide (RBSC) products by slip casting. The way of co-depositing of silicon carbide particles and carbon particles during slip casting process, and the influence of composition of raw particles on particle co-depositing in green bodies were studied. The experiment results show: 1.Co-deposition of binary particles is greatly affected by particle size distribution, and large proportion of rigid SiC particles increases the difficulty in demoulding procedure because of small shrinkage; 2. Dispersants in deposited cake trend to enrich at the surface in contact with mould wall, while this enrichment of dispersant has little effect on mechanical performance of RBSC products; 3. Sharp edges on surface of raw particles could result to friction among particles, which afford strength to green bodies but prevent particles packing more closely.
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Kim, S., S. H. Cho, and H. Park. "Effects of particle size distribution on the cake formation in crossflow microfiltration." Water Supply 2, no. 2 (April 1, 2002): 305–11. http://dx.doi.org/10.2166/ws.2002.0077.
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In crossflow microfiltration, the tendency of particle deposition of polydisperse suspensions has been established experimentally and compared with that of monodisperse suspensions. The mass transfers of particles are different according to size in polydisperse suspensions. The most particles, which deposit to membrane surface without clogging pore in microfiltration, are much larger than 0.1 μm. Among these particles, smaller particles are easier to deposit than larger particles because of shear-induced diffusion and particle deposition depends on the size distribution of small particles. Effective particle diameter is introduced as a representative particle size which can reflect the diffusivity of each particle according to size and it describes the tendency of particle deposition very well in polydisperse suspensions. The effect of effective particle diameter is larger than that of feed concentration. The most important factor affecting particle deposition of polydisperse suspensions is effective particle diameter. The results of our research suggest that the effective particle diameter can be an important factor which can represent the potential for cake formation.
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Iwaoka, Kazuki, Masahiro Hosoda, Shinji Tokonami, Eliza B. Enriquez, Lorna Jean H. Palad, and Reiko Kanda. "DEVELOPMENT OF CALCULATION TOOL FOR RESPIRATORY TRACT DEPOSITION DEPENDING ON AEROSOLS PARTICLE DISTRIBUTION." Radiation Protection Dosimetry 184, no. 3-4 (April 26, 2019): 388–90. http://dx.doi.org/10.1093/rpd/ncz074.
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Abstract Inhalation exposures occur by inhaled radioactive nuclides depositing in the various locations in the respiratory tract (International Commission on Radiological Protection Publication 66). Respiratory tract deposition depends on particle size. The sensitivity to ionising radiation is different among respiratory regions. Under actual atmospheric environments, the radionuclides attach to aerosols of various size in the atmosphere, so the particle size of radionuclides changes differently. Therefore, it is important for the estimation of health impact to calculate the respiratory tract deposition under atmospheric environment wherein the various sizes of radioactive nuclides (i.e. polydisperse particles) exists. In this study, a tool which can calculate the respiratory tract deposition on the basis of polydisperse particle size distribution was developed to estimate dose depending on variable aerosol particle sizes.
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Lu, Hao, Yu Wang, Hongchang Li, and Wenjun Zhao. "Numerical Simulation of Turbulent Structure and Particle Deposition in a Three-Dimensional Heat Transfer Pipe with Corrugation." Energies 17, no. 2 (January 9, 2024): 321. http://dx.doi.org/10.3390/en17020321.
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When colloidal particles are deposited in a heat transfer channel, they increase the flow resistance in the channel, resulting in a substantial decrease in heat transfer efficiency. It is critical to have a comprehensive understanding of particle properties in heat transfer channels for practical engineering applications. This study employed the Reynolds stress model (RSM) and the discrete particle model (DPM) to simulate particle deposition in a 3D corrugated rough-walled channel. The turbulent diffusion of particles was modeled with the discrete random walk model (DRW). A user-defined function (UDF) was created for particle–wall contact, and an improved particle bounce deposition model was implemented. The research focused on investigating secondary flow near the corrugated wall, Q-value standards, turbulent kinetic energy distribution, and particle deposition through validation of velocity in the tube and particle deposition modeling. The study analyzed the impact of airflow velocity, particle size, corrugation height, and corrugation period on particle deposition efficiency. The findings suggest that the use of corrugated walls can significantly improve the efficiency of deposition for particles less than 20 μm in size. Specifically, particles with a diameter of 3 μm showed five times higher efficacy of deposition with a corrugation height of 24 mm compared to a smooth surface.
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Lu, Hao, and Lin Lu. "Investigation of particle deposition efficiency enhancement in turbulent duct air flow by surface ribs with hybrid-size ribs." Indoor and Built Environment 26, no. 5 (August 4, 2016): 608–20. http://dx.doi.org/10.1177/1420326x16662509.
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This study presents the particle deposition enhancement by hybrid-size and same-size surface ribs in turbulent air duct flows using computational fluid dynamics simulation. The Reynolds stress turbulence model with UDF corrections and discrete particle model were adopted to simulate the turbulent air flow fields and particle deposition behaviours, respectively. After numerical validation with the relative literature results, pure particle deposition enhancement ratios, flow drag increase, comprehensive deposition efficiency and deposition enhancement mechanisms were investigated and discussed in details. The findings showed that the hybrid-size ribs with small rib spacing have the best enhancement performance on particle deposition for small particles ([Formula: see text]). Considering the flow drag increase, the maximum deposition efficiency can reach 485 for 1 µm particles for the hybrid-size ribbed cases, while it is just 425 for the same-size ribbed case. Nevertheless, no obvious particle deposition enhancement can be found for large particles ([Formula: see text]) for all types of surface ribs. The hybrid-size surface ribs are more efficient compared with the same-size ribs, which can be applied in the air cleaning equipment to improve the aerosol particle removal performance.
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Niu, Chenchen, Zhen Zhou, Jia Qi, and Xu Yang. "Two-Parameter Probabilistic Model and Experimental Research on Micron Particle Deposition." Applied Sciences 14, no. 14 (July 17, 2024): 6200. http://dx.doi.org/10.3390/app14146200.
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The deposition of micron particles in gas pipelines has always been an important problem in ultra-clean ventilation technology in the modern laser fusion, precision electronics, aerospace, and biomedical fields. Combining the mathematical expression of the migration, collision, and deposition of micron particles in a gas pipeline with a simulation of flow fields, a two-parameter particle probability deposition model based on vinl, θcr and collision probability coefficient PP is established, and the distribution law of particle deposition, considering two deposition targets of the pipe wall and deposition layer, is given. Combined with an experiment on particle migration and deposition in a gas pipeline, an interpretation and verification of the particle deposition distribution law are given, and the difference between the model and experiment is discussed through particle deposition efficiency mass distribution. Studies have shown the following: Under the premise of two kinds of deposition targets, different particle sizes in the gas pipeline present different deposition laws; the deposit morphology is a spot deposit of 10 µm particles and a flake deposit of 40 µm particles; the deposit position shows a uniform distribution and a lower wall dominance; and the deposit concentration area of 40 µm shows a more significant distribution. The results are very important for the selection and optimization of gas pipelines for clean spaces.
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Liu, Zhihao, Jianwu Liu, Haifeng Li, Zizhao Wu, Yuan Zhong, Chidambaram Seshadri Ramachandran, Yingliang Cheng, and Qun Wang. "Research Progress on Numerical Simulation of the Deposition and Deformation Behavior of Cold Spray Particles." Coatings 14, no. 7 (July 21, 2024): 913. http://dx.doi.org/10.3390/coatings14070913.
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It is of significant theoretical and practical value to study the deposition process and deformation behavior of cold-sprayed particles to find the deposition mechanism of cold-sprayed coatings, further improve the coating performance, and expand its application scope. However, observing the deposition process and particle behavior through experiments is difficult due to the brief deposition duration of cold spray particles. Numerical simulation offers a means to slow the deposition process and predict the critical velocity, deformation behavior, bonding mechanism, and residual stress of cold-sprayed particles. This paper uses finite element analysis software, including ANSYS LS Dynamic-2022 R1 and ABAQUS-6.14, alongside various prevalent finite element methods for numerically simulating cold spray particle deposition. These methods involve the Lagrange, Euler, arbitrary Lagrange-Euler (ALE), and Smoothed Particle Hydrodynamics (SPH) to investigate the cold spray particle deposition process. The recent literature primarily summarizes the simulation outcomes achieved by applying these methodologies for simulating the deposition process and deformation characteristics of different particles under varying cold spraying conditions. In addition, the reliability of these simulation results is analyzed by comparing the consistency between the simulation results of single-particle and multi-particle and the actual experimental results. On this basis, these methods’ advantages, disadvantages, and applicability are comprehensively analyzed, and the future simulation research work of particle deposition process and deformation behavior of cold spraying prospects is discussed. Future research is expected to provide a more in-depth study of the micro-mechanisms, such as the evolution of the inter-particle and internal organization of the particles, near the actual situation.
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COMER, J. K., C. KLEINSTREUER, and C. S. KIM. "Flow structures and particle deposition patterns in double-bifurcation airway models. Part 2. Aerosol transport and deposition." Journal of Fluid Mechanics 435 (May 25, 2001): 55–80. http://dx.doi.org/10.1017/s0022112001003810.
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The flow theory and air flow structures in symmetric double-bifurcation airway models assuming steady laminar, incompressible flow, unaffected by the presence of aerosols, has been described in a companion paper (Part 1). The validated computer simulation results showed highly vortical flow fields, especially around the second bifurcations, indicating potentially complex particle distributions and deposition patterns. In this paper (Part 2), assuming spherical non-interacting aerosols that stick to the wall when touching the surface, the history of depositing particles is described. Specifically, the finite-volume code CFX (AEA Technology) with user-enhanced FORTRAN programs were validated with experimental data of particle deposition efficiencies as a function of the Stokes number for planar single and double bifurcations. The resulting deposition patterns, particle distributions, trajectories and time evolution were analysed in the light of the air flow structures for relatively low (ReD1 = 500) and high (ReD1 = 2000) Reynolds numbers and representative Stokes numbers, i.e. StD1 = 0.04 and StD1 = 0.12. Particle deposition patterns and surface concentrations are largely a function of the local Stokes number, but they also depend on the fluid–particle inlet conditions as well as airway geometry factors. While particles introduced at low inlet Reynolds numbers (e.g. ReD1 = 500) follow the axial air flow, secondary and vortical flows become important at higher Reynolds numbers, causing the formation of particle-free zones near the tube centres and subsequently elevated particle concentrations near the walls. Sharp or mildly rounded carinal ridges have little effect on the deposition efficiencies but may influence local deposition patterns. In contrast, more drastic geometric changes to the basic double-bifurcation model, e.g. the 90°-non-planar configuration, alter both the aerosol wall distributions and surface concentrations considerably.
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Zhu, Liangyu, Tao Zhou, Xijia Ding, Xuemeng Qin, and Jialei Zhang. "Study on the Movement and Deposition of Particles in Supercritical Water Natural Circulation Based on Grey Correlation Theory." Energies 12, no. 12 (June 17, 2019): 2315. http://dx.doi.org/10.3390/en12122315.
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The movement and deposition of particles that occur during their natural circulation in supercritical water exercise an important impact on the safe and stable operation of a supercritical water reactor (SCWR). When supercritical water flows in pipelines, a large number of corrosive particles may be generated due to pipeline corrosion or the purity of the fluid itself. The presence of particulate matter affects the heat transfer efficiency of the pipeline, increasing flow resistance and easily promoting heat transfer deterioration. ANSYS-CFX numerical analysis software was used to simulate the natural circulation loop of supercritical water, and micron particles were added in the initial flow field. The effects of heating power, particle concentration and particle diameter on particle deposition were obtained. Through this analysis, it can be concluded that the heating of the pipeline has a certain inhibitory effect on the deposition of particles. The rise in both initial particle concentration and particle diameter serve to reinforce the deposition of particles in the heating section. Depending on the degree of influence, the contributory parameters to particle deposition include particle diameter, particle concentration and heating power in turn.
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Lu, Hao, Zunshi Han, Hongchang Li, Xiqiang Chang, Lijiang Dong, Mao Fan, Dean Kong, and Xuehui Jing. "Simulation of Turbulent Flow Structure and Particle Deposition in a Three-Dimensional Heat Transfer Duct with Convex Dimples." Coatings 13, no. 5 (May 10, 2023): 900. http://dx.doi.org/10.3390/coatings13050900.
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In engineering applications, dust deposition on the heat transfer channel greatly reduces the efficiency of heat transfer. Therefore, it is very significant to study the characteristics of particle deposition for thermal energy engineering applications. In this study, the Reynolds stress model (RSM) and the discrete phrase model (DPM) were used to simulate particle deposition in a 3D convex-dimpled rough channel. A discrete random walk model (DRW) was used for the turbulent diffusion of particles, and user-defined functions were developed for collisions between particles and walls. An improved deposition model of rebound between particles was developed. The flow structure, secondary flow, temperature distribution, Q criterion, and particle deposition distribution in the convex-dimpled rough channel were analyzed after a study of the grid independence and a numerical validation. The results showed that these mechanisms affected the flow structure in the flow field. For tiny particles (dp ≤ 10 μm), the presence of convex dimples promoted their deposition. The rates of particle deposition in the presence of convex dimples were 535, 768, 269, and 2 times higher than in smooth channels (particle sizes of 1, 3, 5, and 10 μm, respectively). However, for large particles (dp > 10 μm), although the presence of convex dimples had a certain effect on the location distribution of particle deposition, it had little effect on the deposition rates of large particles, which were 0.99, 0.98, 0.97 and 0.96 times those in the smooth channel, respectively.
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Pan, Yadi, Shuya Shan, Yao Wei, Feng Ji, Jinping Weng, Yulan Tian, and Jin Qian. "Study on the fiber fouling in drying exhaust heat utilization of wood industry." E3S Web of Conferences 38 (2018): 01003. http://dx.doi.org/10.1051/e3sconf/20183801003.
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Based on the viscoelastic and creep deformation properties, a new deposition mechanism model for slender wood fiber particles in wast heat utilization is proposed in this paper. And the equivalent sphere method is used to describe the particle feature size in the model. With the proposed deposition model of flexible slender particles, the critical criteria are obtained. The influence of particle size, aspect ratio and damping factor on particle deposition has been investigated. The results indicate that particle deposition increases with the particle size decrease, aspect ratio and damping factor increase. According to the present deposition model, a coupling simulation with FLUENT and EDEM method was carried out for the flow field of fiber drying tail gas in heat piping exchanger, which indicated that particle deposition mainly occurred at the central windward area of fin due to the direction changer and the magnitude decrease of collision velocity between fiber particles and wall. Experiment of heat recovery of drying tail gas revealed that using the H fin tubes instead of rectangular fin tubes can greatly relieve the deposition of wood fiber particles, which provided a useful way to save energy in wood industries.
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Whitehead, J. D., G. McFiggans, M. W. Gallagher, and M. J. Flynn. "Simultaneous coastal measurements of ozone deposition fluxes and iodine-mediated particle emission fluxes with subsequent CCN formation." Atmospheric Chemistry and Physics Discussions 9, no. 5 (September 30, 2009): 20567–97. http://dx.doi.org/10.5194/acpd-9-20567-2009.
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Abstract. Here we present the first observations of simultaneous ozone deposition fluxes and ultrafine particle emission fluxes over an extensive infra-littoral zone. Fluxes were measured by the eddy covariance technique at the Station Biologique de Roscoff, on the coast of Brittany, north-west France. This site overlooks a very wide (3 km) littoral zone controlled by very deep tides (9.6 m) exposing extensive macroalgae beds available for significant iodine mediated photochemical production of ultrafine particles. The aspect at the Station Biologique de Roscoff provides an extensive and relatively flat, uniform fetch within which micrometeorological techniques may be utilized to study links between ozone deposition to macroalgae (and sea water) and ultrafine particle production. Ozone deposition to seawater at high tide was significantly slower (vd[O3]=0.302±0.095 mm s−1) than low tidal deposition. A statistically significant difference in the deposition velocities to macroalgae at low tide was observed between night time (vd[O3]=1.00±0.10 mm s−1) and daytime (vd[O3]=2.05±0.16s−1) when ultrafine particle formation results in apparent particle emission. Very high emission fluxes of ultrafine particles were observed during daytime periods at low tides ranging from 50 000 particles cm−2 s−1 to greater than 200 000 particles cm−2 s−1 during some of the lowest tides. These emission fluxes exhibited a significant relationship with particle number concentrations comparable with previous observations at another location. Apparent particle growth rates were estimated to be in the range 17–150 nm h−1 for particles in the size range 3–10 nm. Under certain conditions, particle growth may be inferred to continue to greater than 120 nm over tens of hours; sizes at which they may readily behave as cloud condensation nuclei (CCN) under reasonable supersaturations that may be expected to pertain at the top of the marine boundary layer. These results link direct depositional loss and photochemical destruction of ozone to the formation of particles and hence CCN from macroalgal emissions at a coastal location.
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Whitehead, J. D., G. McFiggans, M. W. Gallagher, and M. J. Flynn. "Simultaneous coastal measurements of ozone deposition fluxes and iodine-mediated particle emission fluxes with subsequent CCN formation." Atmospheric Chemistry and Physics 10, no. 1 (January 13, 2010): 255–66. http://dx.doi.org/10.5194/acp-10-255-2010.
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Abstract. Here we present the first observations of simultaneous ozone deposition fluxes and ultrafine particle emission fluxes over an extensive infra-littoral zone. Fluxes were measured by the eddy covariance technique at the Station Biologique de Roscoff, on the coast of Brittany, north-west France. This site overlooks a very wide (3 km) littoral zone controlled by very deep tides (9.6 m) exposing extensive macroalgae beds available for significant iodine mediated photochemical production of ultrafine particles. The aspect at the Station Biologique de Roscoff provides an extensive and relatively flat, uniform fetch within which micrometeorological techniques may be utilized to study links between ozone deposition to macroalgae (and sea water) and ultrafine particle production. Ozone deposition to seawater at high tide was significantly slower (vd[O3]=0.302±0.095 mm s−1) than low tidal deposition. A statistically significant difference in the deposition velocities to macroalgae at low tide was observed between night time (vd[O3]=1.00±0.10 mm s−1) and daytime (vd[O3]=2.05±0.16 mm s−1) when ultrafine particle formation results in apparent particle emission. Very high emission fluxes of ultrafine particles were observed during daytime periods at low tides ranging from 50 000 particles cm−2 s−1 to greater than 200 000 particles cm−2 s−1 during some of the lowest tides. These emission fluxes exhibited a significant relationship with particle number concentrations comparable with previous observations at another location. Apparent particle growth rates were estimated to be in the range 17–150 nm h−1 for particles in the size range 3–10 nm. Under certain conditions, particle growth may be inferred to continue to greater than 120 nm over tens of hours; sizes at which they may readily behave as cloud condensation nuclei (CCN) under reasonable supersaturations that may be expected to pertain at the top of the marine boundary layer. These results link direct depositional loss and photochemical destruction of ozone to the formation of particles and hence CCN from macroalgal emissions at a coastal location.
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Peng, Yubo, Guoqiang Xu, Xiang Luo, Jian He, and Dongdong Liu. "Particle Deposition in the Vicinity of Multiple Film Cooling Holes." Micromachines 13, no. 4 (March 26, 2022): 523. http://dx.doi.org/10.3390/mi13040523.
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Particle deposition on film cooling surface is an engineering issue that degrades the thermal protection of turbine blade. Here, we present a combined experimental and numerical investigation on the particle deposition in the vicinity of multiple film cooling holes to reveal the effect of interactions between cooling outflows on particle deposition. The numerical simulation of film cooling with a group of three rows of straight film cooling holes is conducted and validated by experimental data with blowing ratios ranging from 0 to 0.08. Wax particles with size range from 5 to 40 μm are added in the heated mainstream to simulate the particle deposition in the experiment. The simulation results show the decrease of particle deposition with blowing ratio and various deposition characteristics in different regions of the surface. The flow fields from numerical results are analyzed in detail to illustrate deposition mechanism of the particles in different regions under the interactions of cooling outflows. The cooling air from the holes in the first row reduces the particle concentration near the wall but causes particle deposition in or between the tail regions by the generated flow disturbance. The cooling air from the latter hole separates the diluted flow in the upstream from the wall, and creates a tail region without particle deposition. This revealed particle deposition characteristics under the effect of outflows interaction can benefit the understanding of particle deposition in engineering applications, where multi-row of cooling holes are utilized.
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Man, Ruiqi, Zhijun Wu, Taomou Zong, Aristeidis Voliotis, Yanting Qiu, Johannes Größ, Dominik van Pinxteren, et al. "Impact of water uptake and mixing state on submicron particle deposition in the human respiratory tract (HRT) based on explicit hygroscopicity measurements at HRT-like conditions." Atmospheric Chemistry and Physics 22, no. 18 (September 21, 2022): 12387–99. http://dx.doi.org/10.5194/acp-22-12387-2022.
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Abstract. Particle hygroscopicity plays a key role in determining the particle deposition in the human respiratory tract (HRT). In this study, the effects of hygroscopicity and mixing state on regional and total deposition doses on the basis of the particle number concentration for children, adults, and the elderly were quantified using the Multiple-Path Particle Dosimetry model, based on the size-resolved particle hygroscopicity measurements at HRT-like conditions (relative humidity = 98 %) performed in the North China Plain. The measured particle population with an external mixing state was dominated by hygroscopic particles (number fraction = (91.5 ± 5.7) %, mean ± standard deviation (SD); the same below). Particle hygroscopic growth in the HRT led to a reduction by around 24 % in the total doses of submicron particles for all age groups. Such a reduction was mainly caused by the growth of hygroscopic particles and was more pronounced in the pulmonary and tracheobronchial regions. Regardless of hygroscopicity, the elderly group of people had the highest total dose among three age groups, while children received the maximum total deposition rate. With 270 nm in diameter as the boundary, the total deposition doses of particles smaller than this diameter were overestimated, and those of larger particles were underestimated, assuming no particle hygroscopic growth in the HRT. From the perspective of the daily variation, the deposition rates of hygroscopic particles with an average of (2.88 ± 0.81) × 109 particles h−1 during the daytime were larger than those at night ((2.32 ± 0.24) × 109 particles h−1). On the contrary, hydrophobic particles interpreted as freshly emitted soot and primary organic aerosols exhibited higher deposition rates at nighttime ((3.39 ± 1.34) × 108 particles h−1) than those in the day ((2.58 ± 0.76) × 108 particles h−1). The traffic emissions during the rush hours enhanced the deposition rate of hydrophobic particles. This work provides a more explicit assessment of the impact of hygroscopicity and mixing state on the deposition pattern of submicron particles in the HRT.
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Cui, Xianze, Quansheng Liu, and Chengyuan Zhang. "Physical factors affecting the transport and deposition of particles in saturated porous media." Water Supply 17, no. 6 (April 13, 2017): 1616–25. http://dx.doi.org/10.2166/ws.2017.065.
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Abstract Saturated sand box experiments were conducted to explore the effect of various physical factors on the transport and deposition of suspended particles in porous media. Red quartz powder and natural quartz sand were employed in the study and acted as suspended particles and porous media, respectively. Particles were injected into the sand box in two modes, i.e., pulse injection and continuous injection. Tests were performed at various particle concentrations, flow velocities, deposition rate coefficient and longitudinal dispersion coefficient by both injection modes. The breakthrough curves were described with the analytical solution of a convection–dispersion equation, in which first-order deposition kinetics were taken into account. Different behavior of suspended-particle transport and deposition in porous media was observed under different injection modes and experimental conditions. The results show that effluent concentration was approximately linear with the initial particle concentration. The deposition rate coefficient depends strongly on particle size and flow velocity, and the transport and deposition process was very sensitive to it. Furthermore, the longitudinal dispersion coefficient increases with increasing flow rate, and particles are easier to transport through pores as the longitudinal dispersion coefficient increases. This study shows the importance of particle concentration, flow velocity, deposition rate coefficient and longitudinal dispersion coefficient in the transport and deposition process of suspended particles.
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Agricola, Koos. "Real-time Particle Deposition Monitoring of Operational Cleanroom Quality." Journal of the IEST 59, no. 1 (January 1, 2016): 40–52. http://dx.doi.org/10.17764/1098-4321.59.1.40.
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Abstract Real-time particle deposition monitoring is a new way to monitor the operational quality of a cleanroom. Up to now the performance of a cleanroom is often monitored with light-scattering airborne particle counters. These give valuable information on airborne particles, but no information on the potentially threatening macroparticles in a cleanroom. In this paper, particle deposition phenomena and ways to determine particle deposition are discussed. A real-time particle deposition monitor using holographic imaging of the witness plates in a sensing device is described. Some practical experiences with real-time particle deposition measurements are demonstrated. Real-time particle deposition monitoring can be a valuable method to control the operational quality of a cleanroom where personnel are working.
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Halter, Wolfgang, Rahel Eisele, Dirk Rothenstein, Joachim Bill, and Frank Allgöwer. "Moment Dynamics of Zirconia Particle Formation for Optimizing Particle Size Distribution." Nanomaterials 9, no. 3 (March 2, 2019): 333. http://dx.doi.org/10.3390/nano9030333.
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We study the particle formation process of Zirconia ( ZrO 2 )-based material. With a model-based description of the particle formation process we aim for identifying the main growth mechanisms for different process parameters. After the introduction of a population balance based mathematical model, we derive the moment dynamics of the particle size distribution and compare the model to experimental data. From the fitted model we conclude that growth by molecular addition of Zr-tetramers or Zr-oligomers to growing particles as well as size-independent particle agglomeration takes place. For the purpose of depositing zirconia-based material (ZrbM) on a substrate, we determine the optimal process parameters such that the mineralization solution contains preferably a large number of nanoscaled particles leading to a fast and effective deposition on the substrate. Besides the deposition of homogeneous films, this also enables mineralization of nanostructured templates in a bioinspired mineralization process. The developed model is also transferable to other mineralization systems where particle growth occurs through addition of small molecular species or particle agglomeration. This offers the possibility for a fast determination of process parameters leading to an efficient film formation without carrying out extensive experimental investigations.
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Liu, Jianhe, and Wenzheng Li. "Experimental study on aerosol inhalation of the human upper airway." BIO Web of Conferences 59 (2023): 03016. http://dx.doi.org/10.1051/bioconf/20235903016.
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The study of aerosol deposition in the human upper respiratory tract is of great significance for understanding the impact of toxic aerosols on human health and improving the therapeutic effect of drug aerosol inhalation. 3D printing technology was used in the experimental model of the human upper airway. A laser particle size analyzer was used to study the deposition of aerosol particles with a particle size of 1-20 μm inhaled in the upper respiratory tract of the human body, and the particle deposition rules of the aerosol particles in the upper respiratory tract were analyzed. The experimental results show that aerosol particles remain more in the pharynx, larynx and position. For particles with a particle size of 1-5 μm, more deposition will occur in the trachea, and for particles with a particle size of 10-20 μm, most of them will be deposited in the mouth.
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Zhang, Xin, Yuesheng Fan, Shuxuan Wei, Huan Wang, Jiaxin Zhang, and Wanqing Yu. "Experimental study on particle deposition in pipelines in a fresh air system." Thermal Science 25, no. 3 Part B (2021): 2319–25. http://dx.doi.org/10.2298/tsci200310121z.
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A semi-empirical formula was recommended to analyze the deposition law of atmospheric particles in pipelines in fresh air systems, where the sizes of particles, inlet velocity, and the air temperature, humidity on the deposition of particulate matters were considered. The results showed when the particle sizes were less than 1.0 ?m, the deposition rate was decreased from the increased in particle sizes. When the particle sizes were larger than 1.0 ?m, the deposition rate was in-creased from the increased in particle sizes. A higher inlet velocity resulted in a greater deposition rate. High humidity or low temperature would also lead to a high deposition rate of dust. The results given in this paper are helpful for optimization of the fresh air system.
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Qian, Fu Ping, and Xian Kun Yu. "Numerical Simulation to Study the Effect of the Particle Deposition Morphology on the Filtration Efficiency of the Fibrous Media." Advanced Materials Research 518-523 (May 2012): 1767–70. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.1767.
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The grid “freezing” method in computational fluid dynamics (CFD) was used to deal with the moving boundary in this study, which can make the dynamic boundary into the fixed boundary and qualitatively describe the particle deposition morphology on the surface of the fibrous media. Meanwhile, the filtration efficiencies of the fibrous media with different deposition particle numbers and particle deposition morphologies were calculated using numerical simulation method. The results show that particle deposition on the surface of the fibrous media can help to improve the filtration performance, and in the steady-state, the effect is not obvious, but in the unsteady-stage, the particle deposition can improve the filtration efficiency greatly. In addition, the disposition morphology that has greater contact area with the oncoming particles is conductive to fibrous media capturing particles.
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Fatt, Yap Yit, and Afshin Goharzadeh. "Modeling of Particle Deposition in a Two-Fluid Flow Environment." International Journal of Heat and Technology 39, no. 3 (June 30, 2021): 1001–14. http://dx.doi.org/10.18280/ijht.390338.
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Particle deposition occurs in many engineering multiphase flows. A model for particle deposition in two-fluid flow is presented in this article. The two immiscible fluids with one carrying particles are model using incompressible Navier-Stokes equations. Particles are assumed to deposit onto surfaces as a first order reaction. The evolving interfaces: fluid-fluid interface and fluid-deposit front, are captured using the level-set method. A finite volume method is employed to solve the governing conservation equations. Model verifications are made against limiting cases with known solutions. The model is then used to investigate particle deposition in a stratified two-fluid flow and a cavity with a rising bubble. For a stratified two-fluid flow, deposition occurs more rapidly for a higher Damkholer number but a lower viscosity ratio (fluid without particle to that with particles). For a cavity with a rising bubble, deposition is faster for a higher Damkholer number and a higher initial particle concentration, but is less affected by viscosity ratio.
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Yin, Xin, Cong Jiang, Yaping Shao, Ning Huang, and Jie Zhang. "Large-eddy-simulation study on turbulent particle deposition and its dependence on atmospheric-boundary-layer stability." Atmospheric Chemistry and Physics 22, no. 7 (April 7, 2022): 4509–22. http://dx.doi.org/10.5194/acp-22-4509-2022.
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Abstract. It is increasingly recognized that atmospheric-boundary-layer stability (ABLS) plays an important role in eolian processes. While the effects of ABLS on particle emission have attracted much attention and been investigated in several studies, those on particle deposition have so far been less well studied. By means of large-eddy simulation, we investigate how ABLS influences the probability distribution of surface shear stress and hence particle deposition. Statistical analysis of the model results reveals that the shear stress can be well approximated using a Weibull distribution, and the ABLS influences on particle deposition can be estimated by considering the shear stress fluctuations. The model-simulated particle depositions are compared with the predictions of a particle-deposition scheme and measurements, and the findings are then used to improve the particle-deposition scheme. This research represents a further step towards developing deposition schemes that account for the stochastic nature of particle processes.
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Hao, Z., X. Yang, and Z. Feng. "Unsteady simulations of migration and deposition of fly-ash particles in the first-stage turbine of an aero-engine." Aeronautical Journal 125, no. 1291 (April 12, 2021): 1566–86. http://dx.doi.org/10.1017/aer.2021.27.
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AbstractParticulate deposits in aero-engine turbines change the profile of blades, increase the blade surface roughness and block internal cooling channels and film cooling holes, which generally leads to the degradation of aerodynamic and cooling performance. To reveal particle deposition effects in the turbine, unsteady simulations were performed by investigating the migration patterns and deposition characteristics of the particle contaminant in a one-stage, high-pressure turbine of an aero-engine. Two typical operating conditions of the aero-engine, i.e. high-temperature take-off and economic cruise, were discussed, and the effects of particle size on the migration and deposition of fly-ash particles were demonstrated. A critical velocity model was applied to predict particle deposition. Comparisons between the stator and rotor were made by presenting the concentration and trajectory of the particles and the resulting deposition patterns on the aerofoil surfaces. Results show that the migration and deposition of the particles in the stator passage is dominated by the flow characteristics of fluid and the property of particles. In the subsequential rotor passage, in addition to these factors, particles are also affected by the stator–rotor interaction and the interference between rotors. With higher inlet temperature and larger diameter of the particle, the quantity of deposits increases and the deposition is distributed mainly on the Pressure Side (PS) and the Leading Edge (LE) of the aerofoil.
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Lee, Seungjae, Seokjun Hong, Haerim Oh, Seung Ki Chae, and Taesung Kim. "Study on Uniform Deposition on 300 mm Silicon Wafer with Sub-100 nm Sized Particles for Cleaning Application." Solid State Phenomena 314 (February 2021): 209–13. http://dx.doi.org/10.4028/www.scientific.net/ssp.314.209.
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A study for uniform deposition on whole area of wafer was conducted to help check the uniformity of cleaning technology between wafer center to edge. A new method of particle deposition was devised different from the conventional studies using the center nozzle and electric field. Our deposition chamber features wafer rotating method and deposition by the principle of convection and diffusion. In this study, we focused on the effect of wafer rotation speed and rotation number to particle deposition result. After setting the optimum condition, fine results with well deposited shape on whole area of the wafer and outstanding particle size uniformity of more than 70% were obtained. Although particle size shift phenomenon occurred in the measurement result using SP5 due to the intrinsic principle, SEM analysis demonstrated that particles with 60, 80 nm sized silica particles were well deposited on wafer. We believe the standard wafer made by our particle deposition system could be utilized and helpful for performance evaluation and development of wafer cleaning technologies.
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Colvin, Jacob, Michael Carter, and James Sears. "Fabrication of Conductors and Inductors by Nano-Particle Deposition through Direct Write Technology." Journal of Microelectronics and Electronic Packaging 3, no. 3 (July 1, 2006): 121–28. http://dx.doi.org/10.4071/1551-4897-3.3.121.
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Direct Write Technologies are being utilized in antennas, engineered structures, sensors, and tissue engineering. One form of the Direct Write Technologies is Maskless Mesoscale Material Deposition (M3D) for Optomec, Inc. M3D is a process that uses aerosol formation, transport and deposition. Inks for the M3D utilize nano-particles in suspension for deposition. Several different conductive inks were deposited with M3D and characterized for electrical resistivity and microstructure. Soft magnetic material was formulated as an ink suspension, deposited and characterized. This paper will report on the results obtained after sintering conductive nano-particle inks and soft magnetic material. Sintering was performed with a 2W frequency doubled Nd:YAG CW laser, a conventional muffle furnace and a novel photonic curing method. Depositions of various conductive inks were examined for physical dimensions (width and thickness) and microstructure. A study of the sintering characteristics if these ink was also included. This paper will also report on the results obtained from depositing a soft magnetic material. Permeability results were calculated from magnetic structures created with the deposition. These results are compared to conventional methods of soft magnetic material formation and construction. Physical properties of the deposited inks are also measured and reported.
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Suo, Xinkun, Shuo Yin, Hua Li, and Rocco Lupoi. "Numerical and Experimental Investigation on Bonding Behavior of Cold Sprayed Porous WC-17Co Particles onto Different Substrates." Coatings 8, no. 10 (October 17, 2018): 367. http://dx.doi.org/10.3390/coatings8100367.
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Cold sprayed WC-Co metal matrix composite coatings have shown great potential in wear-resistance applications. This work aims to use experimental and numerical methods to clarify the deposition and particle–substrate bonding behavior of a single porous WC-17Co particle onto various substrates. To achieve this objective, porous WC-17Co particles were used as the feedstock; soft Al 2024 (Al alloy) and hard stainless steel 316 (SS) were used as the substrates. The experimental results revealed that brittle WC-Co particles tended to remain intact after depositing on a soft Al alloy substrate, but underwent serious fracture when impacting on a hard SS substrate. Further results indicated that the high energy dissipation and the consequent high stress concentration in the WC-Co particle was the main reason for inducing the particle fracture. In addition, two different mechanical interlocking mechanisms were identified during the WC-Co particle deposition process (namely WC reinforcement interlock and WC-Co particle interlock), dominating the particle-substrate bonding. A soft Al alloy substrate resulted in better interlocking than a hard SS substrate, thereby the corresponding particle bonding ratio was also much higher.
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Tan, Kun, Wenjie Hu, Oleksandr Shorinov, and Yurong Wang. "Simulating multi-particle deposition based on CEL method: studing the effects of particle and substrate temperature on deposition." Aerospace Technic and Technology, no. 1 (February 27, 2024): 64–75. http://dx.doi.org/10.32620/aktt.2024.1.06.
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The subject matter of this study is to use numerical simulation methods to study the influence of the temperature of particles and substrates on the post-deposition coating during the multi-particle deposition process of cold spray. The goal is to study the temperature of Al6061 particles and the temperature of the substrate, which are factors that have a greater impact on the deposited coating, and to observe the shape of the coating and the temperature distribution of the cross-section of the substrate after deposition. The tasks to be solved are as follows: use Python scripts to model multi-particles, generate and randomly assign positions according to particle size distribution in the Euler domain, and establish a cold spray multi-particle collision model to simulate the process of cold spray deposition. The following methods were used: The influence of temperature and substrate temperature on the deposited coating was studied through a single variable method; the Coupled Eulerian Lagrangian (CEL) method was used to simulate the collision process of cold-sprayed Al6061 multi-particles. The following results were obtained: changing the temperature of Al6061 particles has a more obvious control effect on the porosity of the deposited coating; after particles of different temperatures impact the constant-temperature substrate, the high-temperature area on the surface of the substrate is mainly located at the junction of pits; after the particle temperature reaches 650K, the coating changes after deposition are no longer significant, indicating an optimal temperature range for Al6061 particle deposition; increasing the temperature of the substrate can increase the depth of particle deposition on the substrate; at the same time, it serves as a reference basis for further using the CEL method to predict the porosity of the Al6061 coating. Conclusions. The scientific novelty of the results obtained is as follows: 1) powder preheating can effectively reduce the porosity of Al6061 coating; 2) the CEL method has good robustness and is used to simulate cold spray multi-particle deposition to monitor the porosity of the coating, which cannot be achieved by the SPH and ALE methods.
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SANKHALA, SHWETA, H. S. SINGH, S. K. SINGH, and GAUTAM LALWANI. "FACTORS THAT AFFECT THE LUNG DEPOSITION." International Journal of Modern Physics: Conference Series 22 (January 2013): 729–32. http://dx.doi.org/10.1142/s2010194513010933.
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The lung is an external organ forming the site of unwanted material or particles. In order to protect it, the airways have to be highly effective filters and if the particle deposit they need to be cleared. Inhaled particles can cause a variety of diseases. There are various factors on which the prediction of depositing particles depends, such as age, particle size, flow rate gender, the physics of the particles, the anatomy of the respiratory tract etc.
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Ding, Tianxiang, Xuyan Hou, Man Li, Guangyu Cao, Jixuan Liu, Xianlin Zeng, and Zongquan Deng. "Investigation on Computing Method of Martian Dust Fluid Based on the Energy Dissipation Method." International Journal of Aerospace Engineering 2020 (May 23, 2020): 1–13. http://dx.doi.org/10.1155/2020/2370385.
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In this paper, an initiative Martian dust fluid simulating research based on the energy dissipation method was developed to simulate the deposition process of Martian dust fluid which was caused by surface adhesion between particles and Martian rovers. Firstly, an energy dissipation model of particles based on the Discrete Element Method (DEM) was established because of the characteristics of Martian dust particles such as tiny size and viscoelasticity. This model is based on the existing DMT model to analyze the collision deposition of dust fluid particles, including particle-spacecraft collision and particle-particle collision. Secondly, this paper analyzed the characteristics of particles after their first collision, then, established the stochastic model of critical wind speed for the particle deposition process. Finally, a series of simulations of the Martian dust fluid particle deposition process were done based on DEM-CFD. The results verified the accuracy of the energy dissipation model and the stochastic model, which could also verify the feasibility and effectiveness of the computing method of Martian dust fluid based on the DEM-CFD technology.
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Donateo, Antonio, Gianluca Pappaccogli, Daniela Famulari, Mauro Mazzola, Federico Scoto, and Stefano Decesari. "Characterization of size-segregated particles' turbulent flux and deposition velocity by eddy correlation method at an Arctic site." Atmospheric Chemistry and Physics 23, no. 13 (July 6, 2023): 7425–45. http://dx.doi.org/10.5194/acp-23-7425-2023.
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Abstract. Estimating aerosol depositions on snow and ice surfaces and assessing the aerosol lifecycle in the Arctic region is challenged by the scarce measurement data available for particle surface fluxes. This work aims at assessing the deposition velocity of atmospheric particles at an Arctic site (Ny-Ålesund, Svalbard islands) over snow, during the melting season, and over dry tundra. The measurements were performed using the eddy covariance method from March to August 2021. The measurement system was based on a condensation particle counter (CPC) for ultrafine particle (UFP; < 0.25 µm) fluxes and an optical particle counter (OPC) for evaluating particle size fluxes in the accumulation mode (ACC; 0.25 < dp < 0.7 µm) and quasi-coarse mode (CRS; 0.8 < dp < 3 µm). Turbulent fluxes in the ultrafine particle size range were prevalently downward, especially in summertime. In contrast, particle fluxes in the accumulation and quasi-coarse mode were more frequently positive, especially during the colder months, pointing to surface sources of particles from, for example, sea spray, snow sublimation, or local pollution. The overall median deposition velocity (Vd+) values were 0.90, 0.62, and 4.42 mm s−1 for UFP, ACC, and CRS, respectively. Deposition velocities were smaller, on average, over the snowpack, with median values of 0.73, 0.42, and 3.50 mm s−1. The observed velocities differ by less than 50 % with respect to the previous literature in analogous environments (i.e. ice/snow) for particles in the size range 0.01–1 µm. At the same time, an agreement with the results of predictive models was found for only a few parameterizations, in particular with Slinn (1982), while large biases were found with other models, especially in the range 0.3–10 µm, of particle diameters. Our observations show a better fit with the models predicting a minimum deposition velocity for small-accumulation-mode particle sizes (0.1–0.3 µm) rather than for larger ones (about 1 µm), which could result from an efficient interception of particles over snow surfaces which are rougher and stickier than the idealized ones. Finally, a polynomial fit was investigated (for the ACC-CRS size range) to describe the deposition velocity observations which properly represents their size dependence and magnitude. Even if this numerical fit is driven purely by the data and not by the underlying chemical–physical processes, it could be very useful for future model parameterizations.
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Liu, Zhengang, Weinan Diao, Zhenxia Liu, and Fei Zhang. "A Numerical Study of the Effect of Particle Size on Particle Deposition on Turbine Vanes and Blades." Advances in Mechanical Engineering 13, no. 5 (May 2021): 168781402110178. http://dx.doi.org/10.1177/16878140211017812.
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Particle deposition could decrease the aerodynamic performance and cooling efficiency of turbine vanes and blades. The particle motion in the flow and its temperature are two important factors affecting its deposition. The size of the particle influences both its motion and temperature. In this study, the motion of particles with the sizes from 1 to 20 μm in the first stage of a turbine are firstly numerically simulated with the steady method, then the particle deposition on the vanes and blades are numerically simulated with the unsteady method based on the critical viscosity model. It is discovered that the particle deposition on vanes mainly formed near the leading and trailing edge on the pressure surface, and the deposition area expands slowly to the whole pressure surface with the particle size increasing. For the particle deposition on blades, the deposition area moves from the entire pressure surface toward the tip with the particle size increasing due to the effect of rotation. For vanes, the particle capture efficiency increases with the particle size increasing since Stokes number and temperature of the particle both increase with its size. For blades, the particle capture efficiency increases firstly and then decreases with the particle size increasing.
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Hua, Dong, Xiqiang Chang, Mengke Liao, Zunshi Han, and Hao Lu. "A CFD Study of Particulate Deposition on Dimple-Type Flue Walls of Coal-Fired Power Plants." Coatings 14, no. 5 (April 24, 2024): 526. http://dx.doi.org/10.3390/coatings14050526.
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The study of particle deposition in bends is always a continuous challenge in various engineering and industrial applications. New types of channels with special microstructures on the surfaces can be effective in modifying the flow field structure as well as particle deposition in channels. In this study, a 90° circular bend with a convex dimple structure was used, and the flow field and the deposition of particles in the channel were analyzed; the Stokes numbers (St) used were 0.016, 0.355 and 1.397. The reliability of the model was ensured by mesh-independence validation as well as speed validation. In a 90° bend channel with convex dimples, the temperature distribution, particle deposition distribution, flow structure and secondary flow were examined. The effects of the number of convex dimples and St in the bend on the flow field structure and particle deposition characteristics were analyzed. The results show that the main factors affecting the deposition characteristics of particles in bends are St, gravitational deposition, thermophoretic force, turbulent vortex clusters and secondary flow distribution. The effect of St is more pronounced, with the deposition rate increasing as the St increases, and the deposition location of the particles is mainly clustered on the outside of the bend structure of the elbow.
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Langenback, E. G., E. H. Bergofsky, J. G. Halpern, and W. M. Foster. "Determining deposition sites of inhaled lung particles and their effect on clearance." Journal of Applied Physiology 68, no. 4 (April 1, 1990): 1427–34. http://dx.doi.org/10.1152/jappl.1990.68.4.1427.
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An essential component of lung defense is clearance of particulates and infectious vectors from the mucus membrane of the tracheobronchial tree and the alveolar regions of the lung. To partition clearance between these areas we determined the bronchial branching pattern, the anatomical sites of particle deposition, and subsequent clearance in the same animal. Using a 2.85-microns particle tagged with 57Co for inhalation and deposition in the sheep lung, we followed clearance via a series of computer-stored gamma-scintillation lung images. The same sheep was reinhaled, and the particle distributions for both inhalations were compared. After the animals were killed, the bronchial branching pattern and length of the bronchial tree were documented. The number of particles depositing in all bronchi down to 1 mm diam was determined by scintillation counting, and the number in respiratory bronchioles and alveoli was microscopically counted. We conclude that particles deposited in bronchi greater than or equal to 1 mm diam clear in 2-4 h postdeposition. Bronchi distal to 1-mm-diam bronchi and alveoli clear evenly over 72 h, and the number of particles equal to the tracheobronchial deposition cleared after 45 h.
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Joo, Hye Sook, Han Shin Choi, Hyung Ho Jo, Hoon Cho, June Seob Kim, and Chang Hee Lee. "Alumina-Titania Spot Spraying Bead Formation and Characteristics in Atmospheric Plasma Spraying." Materials Science Forum 534-536 (January 2007): 401–4. http://dx.doi.org/10.4028/www.scientific.net/msf.534-536.401.
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Fine and coarse alumina-titania composite particles were overlaid by allowing the particles to be deposited for a short time without moving a plasmatron [spot spraying bead]. Both the deposition efficiency and maximum deposition rate were measured at the different plasma gas composition. Considering the normalized maximum deposition rate [(maximum deposition rate)x(deposition efficiency)-1], effects of particle size and plasma gas composition on the particle segregation within a cross-section of mass flux could be estimated. Also, particle melting state according to the position within a mass flux at the moment of impact could be also estimated through the investigations of microstructure and phase composition of the spot spraying bead.
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Zha, Bailin, Xudong Jia, Jinjin Wang, Yi’ang Shi, Qingdong Su, and Tianhao Zhang. "Effect of HVOF particle deposition angle on particle deposition behaviour." IOP Conference Series: Earth and Environmental Science 546 (August 12, 2020): 042057. http://dx.doi.org/10.1088/1755-1315/546/4/042057.
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KIM, DAE-GEUN, and JAE-HO LEE. "KINETIC STUDY OF WC PARTICLES INCORPORATION IN NICKEL COMPOSITE PLATING." Surface Review and Letters 17, no. 03 (June 2010): 359–62. http://dx.doi.org/10.1142/s0218625x10014089.
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The particles, suspended in the electrolyte, can be co-deposited with metal. The co-deposition behaviors of WC and Co-coated WC particles on nickel matrix were investigated. Many operating parameters that influence on the quantity of incorporated particles, including current density, bath agitation and electrolyte composition were investigated. The co-deposition of particles during electroplating depends on the rate of metal deposition and on the flux of particles to the film surface. The growth rate of the metal film is determined by the current density, whereas the flux of particles to the electrode surface is dependent on the particle size, particle concentration in solution, the electrode rotation rate, the particle diffusion coefficient, and the electrode geometry. The kinetic parameters in the co-deposition were calculated from the experimental results. Co-coated WC particles were easily incorporated in the matrix than WC particles from the calculated and experimental results.
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SONG, WOOJIN, KYUBONG JUNG, DOO-MAN CHUN, SUNG-HOON AHN, and CAROLINE SUNYONG LEE. "DEPOSITION OF Al2O3 POWDERS USING NANO-PARTICLE DEPOSITION SYSTEM." Surface Review and Letters 17, no. 02 (April 2010): 189–93. http://dx.doi.org/10.1142/s0218625x10013710.
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In this paper, alumina film was deposited using supersonic micronozzle in nano-particle deposition System (NPDS). Powder deposition at room temperature is important in the field of film deposition since high processing temperature can be a serious limitation for the deposition on flexible substrate. Previously, many studies have been reported on particle deposition, such as aerosol deposition method (ADM) or cold spray method. However, these deposition methods cannot be applied to various types of powders. Recently, NPDS using aluminum nozzle was designed to resolve these problems but it cannot deposit precise patterns less than 1 mm. In this study, alumina particles were deposited using Silicon-based micronozzle in NPDS. Three-dimensional silicon micronozzle was fabricated using semiconductor processing method, specifically deep reactive ion etching (DRIE) method. The silicon micronozzle fabricated by Bosch process is advantageous over the conventionally used nozzle, since the hardness of silicon is higher than that of aluminum and the lifetime can be increased. In this study, alumina nano-particles were accelerated to supersonic level at the neck of micronozzle and deposited on the substrate in a low vacuum condition. The film characteristics were evaluated using field-emission scanning electronic microscope (FE-SEM) and alpha step to measure its thickness of the deposited layer. The deposition result showed that alumina powders were successfully deposited using the fabricated micronozzle by means of NPDS.
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Jassim, Esam. "Particle Entrainment and Deposition Scenario in Sublayer Region of Variable Area Conduit." E3S Web of Conferences 162 (2020): 03006. http://dx.doi.org/10.1051/e3sconf/202016203006.
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The study presents the particle deposition and aggregation phenomena by introducing new parameter called Particle Deposition Number PDN, defined as the ratio of the particle instantaneous velocity to its capturing value. The particle capture or rebound fate will decide from knowing such number. The study employed new scheme of particle deposition in the sublayer region which includes balancing of four forces. Moreover, the bouncing model is also considered for particle fate decision. The study examines the variation of particle velocity at varying area tube and the critical velocity in which particle will tend to stick if its velocity is lower than the threshold limit. The results show that threshold velocity is exponentially decreased with the increment in the particle size. Capturing of particles is shown to be enhanced as the conduit converges due to increasing in the PDN. The analysis of the deposition also investigates the impact of the particle size on the PDN. At low flow velocity, the NDP has V-shaped trend as particle size increases. However, veering toward constant PDN value has occurred as the flow velocity augmented. Finally, small sized particles experience rebound due to the prevailing of the particle impact energy over the adhesion energy before impacting with the surface. The dissipation in the particle energy during impaction causes large sized particle to loose greater amount of energy compare to small sized one, resulting in domination of the adhesion part, which leads to deposition on the surface.
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Bao, Fubing, Hanbo Hao, Zhaoqin Yin, and Chengxu Tu. "Numerical Study of Nanoparticle Deposition in a Gaseous Microchannel under the Influence of Various Forces." Micromachines 12, no. 1 (January 1, 2021): 47. http://dx.doi.org/10.3390/mi12010047.
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Nanoparticle deposition in microchannel devices inducing contaminant clogging is a serious barrier to the application of micro-electro-mechanical systems (MEMS). For micro-scale gas flow fields with a high Knudsen number (Kn) in the microchannel, gas rarefaction and velocity slip cannot be ignored. Furthermore, the mechanism of nanoparticle transport and deposition in the microchannel is extremely complex. In this study, the compressible gas model and a second-order slip boundary condition have been applied to the Burnett equations to solve the flow field issue in a microchannel. Drag, Brownian, and thermophoretic forces are concerned in the motion equations of particles. A series of numerical simulations for various particle sizes, flow rates, and temperature gradients have been performed. Some important features such as reasons, efficiencies, and locations of particle deposition have been explored. The results indicate that the particle deposition efficiency varies more or less under the actions of forces such as Brownian force, thermophoretic force, and drag force. Nevertheless, different forces lead to different particle motions and deposition processes. Brownian or thermophoretic force causes particles to move closer to the wall or further away from it. The drag force influence of slip boundary conditions and gas rarefaction changes the particles’ residential time in the channel. In order to find a way to decrease particle deposition on the microchannel surface, the deposition locations of different sizes of particles have been analyzed in detail under the action of thermophoretic force.
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Wang, Bing, and Jing Lin. "Numerical prediction on deposition of micro-particulate matter in turbulent channel flows." International Journal of Modern Physics C 26, no. 12 (September 2015): 1550134. http://dx.doi.org/10.1142/s012918311550134x.
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A direct numerical simulation of Navier–Stokes equation coupled to the Lagrangian tracking of individual particles was used to predict the dispersion of deposited micro-particulate matter in turbulent channel flows on the walls. The different interaction conditions between particles and walls were considered for particles with Stokes numbers ranging from 0.1 to 104. The particle deposition rates were predicted accurately because of the accurate calculation of turbulence and particle dispersion. It was found the interaction between the turbulent particles and the walls determined the re-entrainment mechanism of inertial particles away from the wall. The dispersion of deposition of particles were independent of the wall conditions in the partial diffusional and whole diffusion-impaction regime, consistent with a log–log law with particle Stokes number, which was found to be [Formula: see text]. The deposition rate decreased with decreasing adhesion of the wall in the inertia-moderated regime. The present results may be helpful for establishing and evaluating accurate prediction models of micro-particle deposition rates in various engineering applications.
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KELBALIEV, Gudrat Isfandiyar ogly, Sakit Rauf ogly RASULOV, and Niyaz Gadym ogly VALIEV. "Mathematical modeling of sedimentation processes and surfacing of solids, droplets and bubbles in an isotropic turbulent flow." NEWS of the Ural State Mining University, no. 4 (December 20, 2020): 123–45. http://dx.doi.org/10.21440/2307-2091-2020-4-123-145.
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Relevance. The problems of separation, stratification and classification of disperse systems that constitute the base of sedimentation and phase displacement are determined by hydrodynamic structure and direction of the flow, physical interaction of forces of different nature of the systems, diffusion transport and deposition in turbulent flows, physical and chemical properties of the particles themselves and the carrier medium and many other factors. Appears the necessity of development of the model of solid spherical particles deposition from a volume with small values of number Re under the condition of absence of effects of interaction of particles and model of constrained deposition from the concentrated disperse flow. The consideration of expressions for determination of effective viscosity of the dispersed system taking into account the concentration of particles in the flow and models of particle deposition from isotropic turbulent flow taking into account the scale of turbulence and specific energy of dissipation. This, in turn, is associated with the determination of the coefficient of resistance for deformable particles (droplets and bubbles), which is used in the model of deposition velocity and surfacing of droplets and bubbles for different numbers of Weber and Morton. Purpose of work. The purpose of this study is an analytical review of all kinds of sedimentation (deposition), separation and stratification of dispersed systems and model representations of their description in different flow conditions. Methodology. To solve given problem, it is necessary to analyze all the effects associated with particle migration, deposition and separation. An essential role in deposition and migration is determined by the forces of resistance, which depend on the number of Reynolds, shape and size, as well as physical and chemical properties of the particles and the corresponding environment. Results. The study of particle deposition in an isotropic turbulent flow for different scales of turbulence in pipes and channels allowed to express the deposition rate through the main parameters of turbulence – specific energy dissipation, scale of turbulence and viscosity of the medium. The deposition and formation of a dense layer of particles on the inner surface of the pipes has a significant influence on all parameters of substance transfer (mass, heat and pulse) and on hydrodynamic stability of the flow. It has been found that the deposition of polydisperse particles is characterized by the size inconstancy or the function of their size distribution, which is related to the confinement of deposition, collision and interaction of particles among themselves. Conclusions. It is concluded that the nature of deposition of particles from the polydisperse turbulent flow is significantly different from their free deposition from the volume. As the result of dispersed particle deposition on the walls of pipes and canals, the following mechanisms and models are distinguished: free-inertial, which is based on the principle of free inertial ejection of particles to the wall; elevating-migration, which binds the deposition of particles with their elevating migration (Magnus effect); convection-inertial, which binds the deposition rate of particles with inertial effects; efficient-diffusion; turbulent-migration, where turbulent migration of particles to the wall is considered as the driving force of deposition. Particle deposition and formation of a dense layer of particles on the inner surface of the pipes has a significant impact on the hydrodynamic flow and heat-mass transfer. Particle deposition and formation of a dense layer of particles on the inner surface of the pipes has a significant impact on the hydrodynamics of the flow and heat and mass transfer. All proposed models are compared with available experimental data, which confirms their effectiveness and adequacy.
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Kang, Soojin, Se-Jin Yook, and Kwan-Soo Lee. "Prediction of particle deposition velocity onto an extreme ultraviolet lithography mask in parallel airflow considering electrophoresis." International Journal of Modern Physics C 25, no. 06 (April 23, 2014): 1450010. http://dx.doi.org/10.1142/s0129183114500107.
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One of the major issues with Extreme ultraviolet lithography (EUVL) is mask defects, which can occur by particle contamination. Gaussian Diffusion Sphere Model (GDSM) was developed to predict particle deposition velocity considering electrophoresis in addition to Brownian diffusion and gravitational settling of particles. For the validation of GDSM, the particle deposition velocities predicted using GDSM were compared with the computational fluid dynamics (CFD) simulation data. The improved GDSM predicted the particle deposition velocity correctly and had fast calculation time. Using the improved GDSM, in an electric field ranging from 0 V/cm to 1000 V/cm, the effects of both attractive electrophoresis and repulsive electrophoresis were evaluated. For the case considering electrophoresis, not only diffusion but also electrophoresis was dominant for the deposition velocity for submicron particles. Repulsive electrophoresis caused the deposition velocity to decrease. However, when the electric field strength was less than 100 V/cm, deposition was not small enough to be ignored. The deposition velocity was analyzed according to free-stream velocity. The effect of free-stream velocity was noticeable under repulsive electrophoresis, whereas it was suppressed under attractive electrophoresis.
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Yin, Zhao-Qin, and Ming Lou. "Experimental study on nanoparticle deposition in straight pipe flow." Thermal Science 16, no. 5 (2012): 1410–13. http://dx.doi.org/10.2298/tsci1205410y.
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Loss of the number of nanoparticles within pipe may lead to significant change of particle number distribution, total mass concentration and particles mean size. The experiments of multiple dispersion aerosol particles ranging from 5.6 nm to 560 nm in straight pipe are carried out using a fast mobility particle sizer. The particle size number distribution, total number concentrations, geometric mean size and volume are acquired under different pipe lengths and Reynolds numbers. The results show lengthening the pipe and strengthening the turbulence can promote the particle deposition process. The penetration efficiency of smaller particle is lower than the larger one, so the particle mean size increases in the process of deposition.
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Yin, Kang, Feng Xiong, and Ke Sun. "Numerical Study of Flow and Particle Deposition in a Block Duct." Journal of Physics: Conference Series 2565, no. 1 (August 1, 2023): 012020. http://dx.doi.org/10.1088/1742-6596/2565/1/012020.
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Abstract The primary of this study is to evaluate the characteristics of airflow organization and particle deposition in blocked ducts with various subgrid models. Five popular sublattice models are chosen to conduct this and the LES method is utilized to simulate the flow field and particle deposition properties of the duct. The results demonstrate that the features of the flow field varied amongst the different sub-grid models. The Smagorinsky and WALE models provide comparable findings, with only one pair of separated vortices in the leeward region. With small separated vortices and a small vortex structure near the wall in the leeward region, the WALES model, the WALES-Omega model, and the KET model are more informative. Simultaneously, a large number of particle groups with particle sizes ranging from 1nm to 50μm were selected for particle phase analysis. It was discovered that the deposition velocity of ultrafine particles below 1μm steadily reduced as particle size grew, whereas the deposition velocity of particles larger than 1μm rose as particle size increased.
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Paul, Akshoy Ranjan, Firoz Khan, Anuj Jain, and Suvash Chandra Saha. "Deposition of Smoke Particles in Human Airways with Realistic Waveform." Atmosphere 12, no. 7 (July 15, 2021): 912. http://dx.doi.org/10.3390/atmos12070912.
Full textAbstract:
Exposure to toxic particles from smoke generated either from bush fire, stable burning, or direct smoking is very harmful to our health. The tiny particles easily penetrate deep into the lungs after exposure and damage the airways. Tobacco smoking causes the direct emission of 2.6 million tons of CO2 and 5.2 million tons of methane annually into the atmosphere. Nevertheless, it is one of the significant contributors to various respiratory diseases leading to lung cancer. These particles’ deposition in the human airway is computed in the present article for refining our understanding of the adverse health effects due to smoke particle inhalation, especially cigarette smoke. Until recently, little work has been reported to account for the transient flow pattern of cigarette smoking. Consideration of transient flow may change the deposition pattern of the particle. A high-resolution CT scan image of the respiratory tract model consisting of the oral cavity, throat, trachea, and first to sixth generations of the lungs helps predict cigarette smoke particle (CSP) deposition. With the same scan, a realistic geometric model of the human airways of an adult subject is used to simulate the transport of air and particle. The CSP deposition is determined at different locations from the oral cavity to the sixth generation of the bronchi. In addition, an unsteady breathing curve indicative of realistic smoking behavior is utilized to represent the breathing conditions accurately. The discrete phase model (DPM) technique is used to determine smoke particle deposition in the human airways. It is found that the deposition increases with the size of the smoke particle. Particles tend to deposit in the oral cavity around the bifurcation junction of the airways. The deposition fraction of CSP with the realistic waveform of smoking is found to be smaller compared to that during the stable flow condition. It is also observed that the fine particles (0.1–1.0 micron) escape to lower generations, leading to higher deposition of fine particles in the deeper airways. The outcome of the study is helpful for understanding smoke-related pulmonary complications.