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The study of the movement of pollutants through ducts facilitates the assessment and control of ambient air quality problems (AQ). Among other things, understanding the deposition and distribution of particulate matter in elbows is important for practical engineering applications. In this study, the turbulent flow field and particle deposition in a 90° bend is investigated using RANS simulation. The RNG k-ε turbulence model was employed to calculate the airflow flow field and the discrete phase model (DPM) was used to simulate the particle phase motion. Where for the discrete phase, the Discrete Random Wander (DRW) model was considered and the deposition of particles with sizes of 1, 3, 5, 10, 20, and 40 μιτι in the flow field was investigated separately. Grid-independent validation of the models used in the simulations was performed. The effects of inlet velocity, particle size, and direction of gravity on the flow field and particle deposition in the elbow were considered. The results show that the flow field in the bend is strongly influenced by the above parameters. Among them, the turbulent disturbance in the bend section is the most intense, with high turbulent energy value, and it is also the region with the largest energy loss. The inlet velocity is negatively correlated with the deposition rate, and the particle size is positively correlated with the deposition rate. [ABSTRACT FROM AUTHOR]

Inhalable particulate drug carriers—nano- and micro-particles, liposomes, and micelles—should be designed to promote drug deposition in the lung and engineered to exhibit the desired drug release property. To deposit at the desired site of action, inhaled particles must evade various lines of lung defense, including mucociliary clearance, entrapment by mucus layer, and phagocytosis by alveolar macrophages. Various physiological, mechanical, and chemical barriers of the respiratory system reduce particle residence time in the lungs, prevent particle deposition in the deep lung, remove drug-filled particles from the lung, and thus diminish the therapeutic efficacy of inhaled drugs. To develop inhalable drug carriers with efficient deposition properties and optimal retention in the lungs, particle engineers should have a thorough understanding of the barriers that particles confront and appreciate the lung defenses that remove the particles from the respiratory system. Thus, this section summarizes the mechanical, chemical, and immunological barriers of the lungs that inhaled particles must overcome and discusses the influence of these barriers on the fate of inhaled particles. [ABSTRACT FROM AUTHOR]

In this study, a realistic model of the respiratory tract obtained from CT medical images was used to solve the flow field and particle motion using the Eulerian–Lagrangian approach to obtain the maximum particle deposition in the bronchial tree for the main purpose of optimizing the performance of drug delivery devices. The effects of different parameters, including particle diameter, particle shape factor, and air velocity, on the airflow field and particle deposition pattern in different zones of the lung were investigated. In addition, a genetic algorithm was employed to obtain the maximum particle deposition in the bronchial tree and the effect of the aforementioned parameters on particle deposition. Reverse flow, vortex formation, and laryngeal jet all affect the airflow structure and particle deposition pattern. The mouth–throat region had the highest deposition fraction at various flow rates. A change in the deposition pattern with an increased deposition fraction in the throat was observed owing to the increased diameter and shape factor of the particles, resulting from the higher inertia and drag force, respectively. The particle deposition analysis showed that three parameters, shape factor, diameter, and velocity, are directly related to particle deposition, and the diameter is the most effective parameter for particle deposition, with an effect of 60% compared to the shape factor and velocity. Finally, the prediction of the genetic algorithm reported a maximum particle deposition in the bronchial tree of 17%, whereas, based on the numerical results, the maximum particle deposition was reported to be 16%. Therefore, there is a 1% difference between the prediction of the genetic algorithm and the numerical results, which indicates the high accuracy of the prediction of the genetic algorithm. [ABSTRACT FROM AUTHOR]

A numerical investigation of the particle deposition characteristics inside film holes and on the blade was conducted using an improved particle deposition model and dynamic grid updating. The computation model was numerically simulated using Reynolds-Averaged Navier-Stokes (RANS) equations with second-order spatial accuracy and the SST k-ω turbulence model, combined User Defined Function (UDF) in FLUENT 2021R1. The influence of the deposition morphology on film effectiveness was analyzed. The results revealed that a conical deposition in the exit region inside the film holes enhanced the separation of the coolant ejected from the film holes at a low coolant mass flux ratio (MFR). Increasing the MFR inhibited deposition, and the enhanced particle detachment significantly reduced particle deposition inside the film holes. Deposition downstream of the film holes significantly affected the cooling performance. Strip deposition on both sides of the region covered by the coolant limited the spanwise diffusion of the coolant. Compared to the non-deposition case, The surface-averaged film effectiveness was lower after deposition at MFRs of 0.1%-0.5% and slightly higher at MFRs of 0.6%. The most significant reduction in the surface-averaged film effectiveness after deposition was 34.9% at an MFR of 0.3%. [ABSTRACT FROM AUTHOR]

Wall deposition is the main problem in a spray dryer that affects the quality of the powder and decreases the dryer operation. In the current study, the influence of using an air pressure nozzle on the conical section of the dryer chamber was examined by simulation of flow pattern in a pilot plant spray dryer using computational fluid dynamics (CFD) technique and Ansys Fluent software (Ver. 17.0). The governing equations are solved in an axisymmetric geometrical model meshed by quadratic elements. Flow pattern was studied and compared in two conditions: before and after considering air pressure nozzle in the dryer chamber wall. Verification of velocity magnitude revealed that there was a little difference (5% to 7%) between numerical and experimental values and there was a good correlation (R²≥ 95%) between them. Flow pattern in the dryer chamber in absence of wall pressure nozzle showed recirculation zones were formed at the end of cylinder part of the chamber. Considering wall pressure nozzle in the model caused deflection of inflow towards the dryer wall and extension of chamber central core flow. The simulation results showed deviation of particle deposition from cone section towards the cylinder and ceiling parts of dryer. [ABSTRACT FROM AUTHOR]

This paper provides an overview of ongoing work aimed at developing spent nuclear fuel (SNF) canister deposition models. Currently, it is known that stainless steel canisters are susceptible to chloride-induced stress corrosion cracking (CISCC). However, the rate of CISCC degradation and the likelihood that it could lead to a through-wall crack is unknown. While it is currently unknown if there is a threshold chloride surface concentration for CISCC initiation, it can be assumed that the onset and progress of material degradation will depend on the local contaminant concentration, the properties of the contaminant species, and the synergistic effects when multiple contaminants are present. This study uses well-developed computational fluid dynamics and particle tracking tools and applies them to SNF storage to determine the rate of deposition on canisters. Understanding the rate of deposition on SNF canisters could be important for making canister aging management predictions. This study is a part of an ongoing effort funded by the U.S. Department of Energy, Office of Nuclear Energy, Office of Spent Fuel and Waste Science and Technology, which is tasked with doing research relevant to enhancing the technical basis for ensuring the safe extended storage and subsequent transport of SNF. This work is being presented to demonstrate a potentially useful technique for SNF canister vendors, utilities, regulators, and stakeholders to utilize and further develop for their own designs and site-specific studies. [ABSTRACT FROM AUTHOR]

Refractory materials are used worldwide in process equipment. However, gaseous and liquid process products penetrate the surface layer and deep into the volume of refractories, destroying rather expensive constructions that are complicated to repair. To address this challenge, there is a need to develop protective coatings for refractory materials that can limit the penetration of working media and extend their operational lifespan. In this work, the application of gas-dynamic cold spraying (CGDS) to produce a coating on the refractory materials using fine titanium dioxide (TiO2) particles is explored. These particles are accelerated within a nitrogen flow, passing through a Laval nozzle, and then sprayed onto a fireclay surface. The mechanisms of particle deposition and layer formation on porous surfaces through experiments and numerical simulations were investigated. The geometry of a typical refractory pore was determined, which was then incorporated into computational fluid dynamics (CFD) simulations to model the cold spraying process of porous substrates. As a result, the influence of the particle size on its velocity and angle of penetration into pores was established. Experimental findings demonstrate the effective closure of pores and the formation of a particle layer on the refractory surface. Furthermore, the nanoindentation tests for the refractory samples showcase capabilities for checking coating thickness for porous materials. [ABSTRACT FROM AUTHOR]

A numerical investigation of the particle deposition characteristics inside film holes and on the blade was conducted using an improved particle deposition model and dynamic grid updating. The computation model was numerically simulated using Reynolds-Averaged Navier-Stokes (RANS) equations with second-order spatial accuracy and the SST k-ω turbulence model, combined User Defined Function (UDF) in FLUENT 2021R1. The influence of the deposition morphology on film effectiveness was analyzed. The results revealed that a conical deposition in the exit region inside the film holes enhanced the separation of the coolant ejected from the film holes at a low coolant mass flux ratio (MFR). Increasing the MFR inhibited deposition, and the enhanced particle detachment significantly reduced particle deposition inside the film holes. Deposition downstream of the film holes significantly affected the cooling performance. Strip deposition on both sides of the region covered by the coolant limited the spanwise diffusion of the coolant. Compared to the non-deposition case, The surface-averaged film effectiveness was lower after deposition at MFRs of 0.1%-0.5% and slightly higher at MFRs of 0.6%. The most significant reduction in the surface-averaged film effectiveness after deposition was 34.9% at an MFR of 0.3%.

This research aims to evaluate the effect of porous filter configuration on flow characteristics within filter using CFD simulation. This simulation model was chosen for comprehensive analysis that considers different variables affecting the filter performances. Dynamics of the flow and pressure drop under different flow conditions and filter geometry were studied. The Euler-Lagrangian approach was used to model multiphase flow, and the standard K-ε model was used for turbulence characterisation. Particle size distribution was characterized using Rosin-Rammler distribution. The initial status of these properties was obtained by previous experimental references and their evolution over time was simulated at the cell level of the model using User-Defined Functions (UDF). The main conclusions of the study are: i) The pressure drop increased with flow rate and thickness of the filter but decreased with increasing filter length and diameter. ii) There is no significant change in velocity ratio with the distance from the filter inlet at the filter centre line except the first 5% from the inlet and last 5% close to the end. iii) it was identified that higher radial velocity ratios imply a less particle deposition within the filter media. The results also shows that the particle loading on 290 mm filter is 50% - 60% lower than the other filters but evenly distributed across the filter. However, the pressure drop decreased with the filter length. 55mm filter that has the highest radial velocity ratio performs poorly in particle trapping.

The deposition of fly ash on the heat exchanger will reduce the heat transfer efficiency of the system. This article conducted experiments and simulations on the deposition, exploring the effects of velocity, particle size on the deposition position. In addition, deposition density distribution was demonstrated, the calculation method of fin thermal resistance was improved, and the efficiency of fins was also calculated. The results showed that deposition decreased with velocity increasing, and the simulation results were in good agreement with the experimental results. The deposition distribution of the first section of the fin is unimodal, and the maximum deposition value approaches the peak of the fin. The distribution of the second section of the fin becomes bimodal with increasing velocity. In addition, as the speed increases, due to the decrease in deposition mass, the thermal resistance decreases by 53.2% and the fin efficiency increases by 8.82%. [ABSTRACT FROM AUTHOR]

The objective of the current study was to investigate the impact of human's height variability to the deposition percentage, the deposited and the retained dose of particulate matter in the respiratory tract. In addition, the dose to the oesophagus, blood and lymph nodes was evaluated after particle clearance. A methodology which correlates anatomical and physiological parameters with height was adopted into an existing particle dosimetry model (Exposure Dose Model 2, ExDoM2). Model results showed that deposition of particles with aerodynamic diameter (dae) ranging from 0.001 to 10 μm depends on the competition between anatomical/physiological parameters, with the maximum effect induced from height variability to be observed for particles in the size range of 0.30 μm ae <1.5 μm. Specifically, a decrease in the subject's height by 100 cm (from 175 to 75 cm) caused a 60.5 ± 6.8% increase in the total deposition percentage during light exercise. Contrarily, an increase in the subject's height by 100 cm (from 75 to 175 cm) caused a 376% increase in the daily deposited dose of PM10 in the respiratory tract. Investigating the inter-subject variability of PM10 dose showed that the extrathoracic region was characterized by lower variability (10.0%) compared to the thoracic region (16.2%). After clearance, the highest variability was observed for blood (15.7%), followed by the respiratory tract (12.1%), lymph nodes (10.4%) and oesophagus (10.1%). Results of the current study highlight the impact induced by incorporating height to scale the inter-subject variability in particle deposition and dose in the human body. [ABSTRACT FROM AUTHOR]

The human nasal cavity develops from birth with size anatomical changes. This study aims to evaluate the flow parameters and particle deposition parameters. Neonatal and infant nasal cavities are developed using MIMICS 21.0, and the flow is evaluated by ANSYS 2021 R2 using CFD to evaluate velocity, pressure, micro- and nanoparticle depositions under sedentary breathing conditions. Neonatal nasal valve velocity was recorded 3.5 times higher compared to the infant for 1.8 LPM and 2.7 times for 3 LPM. Neonatal vestibular depositions up to 10 µm were 6.6%, which increased to 76% for 60 µm for 1.8 LPM and increased to 21.3% for 10 µm and 79% for 60 µm for 1.8 LPM. The neonatal nasal valve showed maximum depositions of around 35% for 20 µm for both flow rates. Maximum depositions of nanoparticles are in the mid-nasal region. Infant nasal cavities deposit around 1% to 2% for nanoparticles below 20 nm for both flow rates. Neonatal overall microparticle depositions doubled with an increase in flow rate up to 10 µm. The overall deposition efficiency of nanoparticles increases 1.5 times with increasing flow rate. This study will help with the medical administration of aerosol-based medications in the patient and age-specific nasal cavity. [ABSTRACT FROM AUTHOR]

Anisotropic conductive adhesives (ACAs) are the preferred interconnection technology for applications that employ large dies, flexible substrates, and ultra fine‐pitch interconnects. Conventional ACAs require relatively high bonding pressures and temperatures, and ultra fine‐pitch applications challenge the trade‐off between low interconnect resistance and risk of short circuits. This study introduces an ACA‐like interconnection technology that addresses these limitations, allowing for low‐pressure, low‐temperature assembly processes with enhanced particle control at the interconnects. Conductive particles are deposited onto a patterned carrier and subsequently transferred to electrical pads using either non‐conductive film or Ag sintering. The Ag sintering process is performed at a low temperature (140 °C) and low bonding pressure (1 N for a 10 × 10 mm2 chip). The capability of controlling the position and number of conductive particles within individual interconnects is demonstrated. This presents possibilities for achieving ultra‐fine pitch interconnects with negligible risk of short circuits, without compromising electrical resistance. It is demonstrated that interconnect resistance can be tuned by varying the number of conductive particles (achieving a resistance as low as 33 mΩ with 25 particles per interconnect). This approach is applicable to scenarios where the bonding force and temperature must remain low due to the nature of substrate materials. [ABSTRACT FROM AUTHOR]

Objective: To review the existing literature on the application of computational fluid dynamics methods to study nasal particle deposition and to summarize and analyze the factors affecting nasal particle deposition in order to provide theoretical references for the development of future transnasal drug delivery devices and the prevention of respiratory‐related diseases. Data Source: PubMed and CNKI databases. Methods: A search of all current literature (up to and including February 2023) was conducted. Search terms related to the topic of factors influencing nasal particle deposition were identified, and queries were conducted to identify relevant articles. Results: Both the properties of the particles themselves and the environmental conditions external to the particles can affect particle deposition in the nasal cavity, with particle deposition showing a positive correlation with particle size, particle density, and airflow velocity, with increasing subject age leading to a decrease in deposition, and with the relationship between airflow temperature and humidity still requiring more research to further explore. Conclusions: With the popularity of computational fluid dynamics, more and more scholars have applied computational fluid dynamics technology to explore the influence of different parameters on particle deposition. By summarizing and analyzing the influence law of various factors on deposition, it can provide a theoretical basis for the future development and application of transnasal drug delivery devices and the prevention of respiratory‐related diseases, which makes a significant contribution to the optimization of clinical disease prevention and treatment. Level of Evidence: NA. [ABSTRACT FROM AUTHOR]

The transport and deposition of particles accompanying the heat setting process in the opposed jet air supply system have a significant impact on the equipment safety. This paper used the Realizable k–ε model to simulate the flow field distribution of the impinging jet and the Lagrange method to track the trajectory of particles, by considering factors, such as jet velocity (7–13 m/s), oven temperature (413–473 K), and particle size (1–30 μ m) changes, the instantaneous force process of particles was analyzed and their deposition mechanism was revealed. The numerical results have been well validated, with the root mean square error of within 10%. The results indicate that the flow field form of the opposed jet significantly affects particle placement on the surface of the air duct, the maximum turbulent vortex structure appears at the inlet of the air duct on both sides of the protruding nozzle, enhancing the capture of particles. Under the influence of gravity, the lower surface of the air duct becomes the main deposition surface, this phenomenon becomes more pronounced as the particle size increases and the maximum deposition rate difference between the upper and lower layers is 37%. The number of particles deposited on the rear end of the air duct is greater than that on the front end, and the deposition rate decreases with the increase in jet velocity. In the initial stage, a temperature gradient appeared in the machine room, which provided upward lift for the particles, resulting in more small diameter particles ( d p < 10 μ m) depositing on the upper surface of the air duct. The results can provide theoretical support for the fire prevention and pollutant purification of equipment, such as heat setting machines. [ABSTRACT FROM AUTHOR]

Nowadays, dust exposure pollution is receiving a lot of attention due to its significant impact on public health. To investigate the impact of dust particle size and human respiratory strength on respiratory particle deposition patterns, data was collected through on‐site surveys. The study analyzed the equivalent respiratory strength, dust environment characteristics, and bronchial particle escape and deposition patterns of humans in fully mechanized mining faces at various operating times. This was done using ergonomic energy consumption simulation experiments and a fluid–solid interaction method of CFD‐DEM. The findings revealed that as humans worked continuously for 5, 15, 30, 45, and 60 min, their respiratory intensity corresponded to 8, 18, 30, 42, and 50 L/min, respectively. According to the field investigation and particle size analysis, the particle size distribution of 1~5, 5~10, 10~20, 20~30, and 30~40 μm particles accounted for 36%, 26%, 15%, 11%, and 10%, respectively. In general, the deposition rate of dust was highest in the main bronchus of the respiratory tract, followed by the trachea area. Particles ranging from 5 to 10 μm in size were observed to have a higher likelihood of escaping from the tertiary bronchioles and entering the secondary bronchial regions. Conversely, particles larger than 20 μm exhibited a deposition rate of up to 80% in the tertiary bronchial regions. It was noted that the bronchial deposition rate of particles of varying sizes increased with respiratory strength, with smaller particles showing greater sensitivity to changes in respiratory strength in terms of the deposition fraction. Among the different particle sizes, the deposition rate of 5–10 μm particles exhibited the most variation with increasing respiration intensity, ranging up to 17%. [ABSTRACT FROM AUTHOR]

This study employed computational fluid dynamics-discrete phase model (CFD-DPM) to investigate the transport characteristics of transient high-temperature dust in a vertical tee duct. Utilizing the large eddy simulation (LES) model, the research elucidated the flow characteristics, temperature field distribution, and particle deposition patterns within the tee duct. Specifically, it was observed that the vortex generated by the tee duct dissipated when x/D exceeds 20. Furthermore, high-temperature fluid exhibited an upward migration within the pipe by buoyancy, concurrently intensifying flow velocity fluctuations. Particle diffusion was initially driven by particle inertia and later became dominated by the combined effects of vortex and buoyancy. The deposition of particles displayed a trend of a sharp increase and decrease, then a gradual increase and decrease along the duct. The particle deposition can be divided into three stages, each governed by varying influencing factors on particle movement: (a) particle inertia within the range 0 < x/D < 5; (b) vortex carry spanning 5 < x/D < 20; and (c) turbulent pulsations beyond 20 < x/D. The total deposition mass was decreased by 50% by the vortex. This article provides a comprehensive description of the diffusion and deposition of transient high-temperature dust in a tee duct. [ABSTRACT FROM AUTHOR]

Whey is a very perishable food and a potent source of protein. It might be more commercialized through the process of spray drying, which would enhance its shelf life. No CFD computational models applied to the drying of fresh sweet whey have been reported in the literature to investigate transport phenomena in spray dryers and to predict crucial design parameters such as deposition, powder recovery, and drying efficiency. Using an Eulerian-Langragean technique, the behavior of multiphase flow as well as heat and mass transfer were investigated. The influence of the inlet air temperature was evaluated in relation to the velocity profiles of the continuous and discrete phases, the residence time distribution, the particle diameter formed, the air temperature near the injection zone, the particle temperature, and the mass fraction of evaporated water. Furthermore, performance parameters such as powder recovery, particle deposition, and drying efficiency were projected for varied air inlet temperatures. The velocity, residence time, and particle size distribution patterns were similar for the different air inlet temperatures. Greater variations might be noticed in the injection zone, especially in the temperature and mass fraction profiles. The lowest drying temperature resulted in the lowest particle deposition and the best thermal efficiency, making it the optimal process condition. This investigation can serve as a benchmark for the design of optimized spray dryers with greater thermal efficiency and yield to produce powdered whey.

Coal particles carried by the gas extraction flow are easy to be deposited in the mining-induced fracture, which seriously reduces the flow rate of gas extraction. Mastering the deposition characteristics of particles in the fracture is an important basis for improving the flow rate of gas extraction. In this paper, we carried out a particle transport and deposition experiment in the fracture with a shrinkage, and studied the particle deposition bed evolution law after crossing the shrinkage under the influence of the gas extraction flow. In addition, we analyzed the influence of the gas velocity and shrinkage structure parameter on the particle deposition law of the back end of the shrinkage of the fracture and the local resistance of the gas flow. The results show that the granular sedimentary bed at the back end of the fracture shrinkage shows two kinds of evolution patterns. When the particle deposition bed is distributed in a “V” shape along the airflow direction, the deposition height of the granular deposition bed shows an evolution pattern of rapid increase followed by a slow decrease. When the depositional zone is a “Ʌ” shaped deposition along the direction of flow, the depositional height shows an evolutionary pattern of slow increase and then slow decrease. In addition, with the development of the particle bed in the fracture, the local resistance changes at the back end of the fracture shrinkage can be divided into the initial stabilization stage, the rapid development stage and the final stabilization stage. The evolution time of the initial stabilization stage is shortened with the increase of the pumping rate or the decrease of the shrinkage ratio. The evolution time of the rapid development stage is shortened with the increase of the pumping rate or the increase of the shrinkage ratio.

This study explores the ternary nanofluid flow within the canonical gap between a cone and a disk with particle deposition and magnetic field effects. Reduced titanium dioxide, magnetite, and graphene oxide are used as nanoparticles in the base fluid ethylene glycol. The governing equations of the problem are in the form of partial differential equations, which are converted to nonlinear ordinary differential equations by using appropriate similarity transformations, and they are solved numerically by using Runge–Kutta–Fehlberg fourth fifth-order (RKF 45) technique. The main agenda of this work is to discuss the impacts of parameters on three cases. The effects of essential aspects on fluid flow, heat and mass transfer rates were studied and analyzed using a graphical representation. Additionally, the response surface methodology and sensitivity analysis are carried out to enhance the importance of the heat transfer rate. The results reveal that the flow field increases significantly with increased Reynolds numbers for both cone and disk rotations. It is observed that the sensitivity analysis of the Nusselt number toward the Eckert number is more for all the radiation parameter values and the Eckert number’s middle level. [ABSTRACT FROM AUTHOR]

Protein‐based therapeutics and vaccines play a pivotal role in the realm of biomedical science. Pulmonary administration offers several advantages including rapid adsorption, non‐invasive, increased local drug concentration, and bypassed first‐pass metabolism, thus holding great potential to address multiple unmet medical needs in lung‐related diseases and vaccination. However, the limited success of inhaled proteins in clinical settings highlights the challenges associated with protein stability and the physiological barriers within the respiratory system. To overcome these hurdles, a variety of delivery systems including polymers, liposomes, cell‐derived membranes, and inorganic materials are developed to improve the stability, mucus penetration, retention time, and bioavailability of proteins. With the outbreak of COVID‐19, the pulmonary administration of proteins has drawn great attention. In this review, the design principle, preparation, biomedical application, progress in clinical translation, advantages, and disadvantages of each kind of delivery system are summarized, with an emphasis on carrier materials. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Understanding the coupling effect of multiple factors on particle deposition above the near-wall heat source is vital for human health, manufacturing, treasure protection and so on. This study investigated the concentrations and decay rate loss coefficient of particles in an experimental chamber with different heat-source configurations. Thirty-nine cases were created by changing the surface temperature and the shape of the near-wall heat source as well as the angular velocity of the six-bladed fan. The results reveal that the temperature, relative humidity, air velocity and the shape of the near-wall heat sources all exhibit different degrees of influence on the particle deposition. Also, the impacts of these factors on particle deposition on the vertical wall above near-wall heat sources can be further influenced by the size and location of particles. [ABSTRACT FROM AUTHOR]

Transpiration cooling based on a porous structure has an ultra-high cooling efficiency, which is expected to be one solution to improve the cooling technology of aero-engine turbine blades. However, particulate impurities in the gas flow channel continue to deposit on the surface of turbine components, blocking cooling holes, which causes great harm to the cooling of turbine blades. In this study, a sintered metal mesh plate was selected as the transpiration cooling structure, and the evolution of particle deposition quality and deposition thickness on the transpiration cooling surface with time, as well as spatial distributions of particle deposition thickness at different times, were explored through experimental and simulation methods. The results showed that, with the increase in spray time, deposition quality and maximum deposition thickness of the transpiration cooling surface gradually increased. Along the main-stream direction, when spray time was short, deposition thickness was higher in a narrow range upstream of the experimental specimen. With the increase in spray time, deposition thickness gradually decreased along the direction of the transpiration cooling mainstream. In the spanwise direction, when spray time was very short, deposition thickness in the spanwise direction was more consistent and, after spray time increased further, the deposition thickness distribution began to tend to a "∩"-type distribution. It can be seen from the simulation results of the metal wire mesh particle deposition that particles were easily deposited on the windward side of the metal wire in the main-stream direction, which agreed with the experimental distribution characteristics of the metal wire mesh deposition. Moreover, the increase in blowing ratio reduced the deposition of particles on the wall of the metal wire mesh. [ABSTRACT FROM AUTHOR]

Urban vegetation plays a crucial role in reducing atmospheric particulate matter (PM), modifying microclimates, and improving air quality. This study investigates the impact of a laurel hedge (Laurus nobilis L.) on airborne PM, specifically total suspended particulate (TSP) and respirable particles (PM4) generated by a Diesel tractor engine. Conducted in a wind tunnel of approximately 20 m, the research provides insights into dust deposition under near-real-world conditions, marking, to our knowledge, the first exploration in a wind tunnel of this scale. Potted laurel plants, standing around 2.5 m tall, were arranged to create barriers of three different densities, and air dust concentrations were detected at 1, 4, 9, and 14 m from the plants. The study aimed both to develop an experimental system and to assess the laurel hedge's ability to reduce atmospheric PM. Results show an overall reduction in air PM concentrations (up to 39%) due to the presence of the hedge. The highest value of dust reduction on respirable particles was caused by the thickest hedge (three rows of plants). However, the data exhibit varying correlations with hedge density. This study provides empirical findings regarding the interaction between dust and vegetation, offering insights for designing effective hedge combinations in terms of size and porosity to mitigate airborne particulate matter. [ABSTRACT FROM AUTHOR]

Pipeline conveying is a crucial method for realizing gangue slurry filling. In order to avoid the blockage of gangue slurry in pipeline conveying, it is necessary to clarify the deposition behavior of gangue particles in the pipeline. This paper analyzes coal gangue's microstructure and mineral composition in the Zhaozhuang No. 2 coal mine through electron microscope scanning and X-ray diffraction tests. We studied the viscosity characteristics of gangue slurry at different mass concentrations and particle sizes and analyzed the change rule of viscosity of gangue slurry with time. Based on determining the nature of the slurry material, a simulation analysis of the deposition behavior of the gangue slurry in a pipeline was carried out using the coupled fluid dynamics–discrete element (CFD-DEM) method. The results show that gangue slurry with a particle size larger than 1.0 mm is likely to lead to the blockage of the pipeline. A small increase in viscosity will promote a uniform distribution of particles inside the pipeline. The deposition behavior of particles is jointly influenced by gravity, fluid interaction force, inter-particle force, and the interaction between particles and the pipeline surface. The research results can be used as a reference for the design and study of gangue slurry grouting systems. [ABSTRACT FROM AUTHOR]

The two-stage electrostatic precipitator is widely used to purify oil mist particles. However, there is limited research on the influences of relative humidity, particle deposition characteristics, and the generation of gaseous pollutants. Therefore, this paper established a numerical model of the electrostatic oil mist purifier and applied it to a two-stage electrostatic precipitator. Then the model was used to investigate the corona discharge characteristics under different relative humidity conditions in the charged zone, the particle deposition characteristics, the purification efficiency, the ozone concentration distribution, and the oil vapor concentration distribution in the collection zone. The results indicate that, with a constant temperature, the corona current decreases as relative humidity increase, and there is a quadratic relationship between relative humidity and current. The variation in relative humidity has little impact on the purification efficiency. The maximum ozone concentration occurs near the electrode line, and its concentration is influenced by the discharge current and inlet airflow velocity. The oil vapor concentration reaches its maximum value at the side plates, with a value of 19 ppb, while it reaches the minimum value at the collecting zone electrode plate, with a value of 2 ppb. The temperature is the main factor affecting the volatilization of the oil film, with higher temperatures resulting in higher oil vapor. [ABSTRACT FROM AUTHOR]

Abstract Objective To review the existing literature on the application of computational fluid dynamics methods to study nasal particle deposition and to summarize and analyze the factors affecting nasal particle deposition in order to provide theoretical references for the development of future transnasal drug delivery devices and the prevention of respiratory‐related diseases. Data Source PubMed and CNKI databases. Methods A search of all current literature (up to and including February 2023) was conducted. Search terms related to the topic of factors influencing nasal particle deposition were identified, and queries were conducted to identify relevant articles. Results Both the properties of the particles themselves and the environmental conditions external to the particles can affect particle deposition in the nasal cavity, with particle deposition showing a positive correlation with particle size, particle density, and airflow velocity, with increasing subject age leading to a decrease in deposition, and with the relationship between airflow temperature and humidity still requiring more research to further explore. Conclusions With the popularity of computational fluid dynamics, more and more scholars have applied computational fluid dynamics technology to explore the influence of different parameters on particle deposition. By summarizing and analyzing the influence law of various factors on deposition, it can provide a theoretical basis for the future development and application of transnasal drug delivery devices and the prevention of respiratory‐related diseases, which makes a significant contribution to the optimization of clinical disease prevention and treatment. Level of Evidence NA.

The study of the movement of pollutants through ducts facilitates the assessment and control of ambient air quality problems (AQ). Among other things, understanding the deposition and distribution of particulate matter in elbows is important for practical engineering applications. In this study, the turbulent flow field and particle deposition in a 90° bend is investigated using RANS simulation. The RNG k-ε turbulence model was employed to calculate the airflow flow field and the discrete phase model (DPM) was used to simulate the particle phase motion. Where for the discrete phase, the Discrete Random Wander (DRW) model was considered and the deposition of particles with sizes of 1, 3, 5, 10, 20, and 40 μm in the flow field was investigated separately. Grid-independent validation of the models used in the simulations was performed. The effects of inlet velocity, particle size, and direction of gravity on the flow field and particle deposition in the elbow were considered. The results show that the flow field in the bend is strongly influenced by the above parameters. Among them, the turbulent disturbance in the bend section is the most intense, with high turbulent energy value, and it is also the region with the largest energy loss. The inlet velocity is negatively correlated with the deposition rate, and the particle size is positively correlated with the deposition rate.

Urban vegetation plays a crucial role in reducing atmospheric particulate matter (PM), modifying microclimates, and improving air quality. This study investigates the impact of a laurel hedge (Laurus nobilis L.) on airborne PM, specifically total suspended particulate (TSP) and respirable particles (PM4) generated by a Diesel tractor engine. Conducted in a wind tunnel of approximately 20 m, the research provides insights into dust deposition under near-real-world conditions, marking, to our knowledge, the first exploration in a wind tunnel of this scale. Potted laurel plants, standing around 2.5 m tall, were arranged to create barriers of three different densities, and air dust concentrations were detected at 1, 4, 9, and 14 m from the plants. The study aimed both to develop an experimental system and to assess the laurel hedge’s ability to reduce atmospheric PM. Results show an overall reduction in air PM concentrations (up to 39%) due to the presence of the hedge. The highest value of dust reduction on respirable particles was caused by the thickest hedge (three rows of plants). However, the data exhibit varying correlations with hedge density. This study provides empirical findings regarding the interaction between dust and vegetation, offering insights for designing effective hedge combinations in terms of size and porosity to mitigate airborne particulate matter.

Dysphonia is very common worldwide and aerosol drug inhalation is an important treatment for patients with dysphonia. This study aimed to explore the effects of vocal fold (VF) lesions on the particle deposition pattern using computational modeling. A realistic mouth-throat (MT) model of a healthy adult was constructed based on computed tomography images. Small and large vocal fold lesions were incorporated in the original model. A steady inhalation flowrate of 15 and 30 liter per minute (LPM) was used as the velocity inlet and monodisperse particles with diameters of 5 to 10 µm were simulated. Particles of larger size are more likely to be deposited in MT models, most of them distributed in oral cavity, oropharynx and supraglottis. The ideal sizes at 30 LPM ranged over 7-10 µm for healthy VFs and 6-8 µm for VF lesions. The best sizes at 15 LPM ranged over 6-8 µm for healthy VFs and 8-9 µm for VF lesions. Based on this study, VF lesions influence the deposition pattern in the glottis obviously. The ideal sizes differ at the flow rates of 15 and 30 LPM. [ABSTRACT FROM AUTHOR]

In this study, both experiments and computational fluid dynamics simulations were performed to investigate the transport characteristics of transient high-temperature dust in a tee duct. The experimental results showed that there is a cavity downstream of the main duct. The simulation results showed that the second flow was generated downstream, and the high-temperature dust moved to the top of the main duct owing to thermal expansion and buoyancy. The temperature change in the particles depended on the site, and the temperature of the particles in the center was higher than that of the surrounding particles. The thermal expansion and buoyancy of high-temperature fluids affected the particle motion through the drag force. The deposition of particles was wing-like and was mainly present on both sides of the tee duct, which was five times the diameter of the main duct. This study provides theoretical guidance for the development of industrial ventilation systems. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Pharmaceutical aerosols play a key role in the treatment of lung disorders, but also systemic diseases, due to their ability to target specific areas of the respiratory system (RS). This article focuses on identifying and clarifying the influence of various factors involved in the generation of aerosol micro- and nanoparticles on their regional distribution and deposition in the RS. Attention is given to the importance of process parameters during the aerosolization of liquids or powders and the role of aerosol flow dynamics in the RS. The interaction of deposited particles with the fluid environment of the lung is also pointed out as an important step in the mass transfer of the drug to the RS surface. The analysis presented highlights the technical aspects of preparing the precursors to ensure that the properties of the aerosol are suitable for a given therapeutic target. Through an analysis of existing technical limitations, selected strategies aimed at enhancing the effectiveness of targeted aerosol delivery to the RS have been identified and presented. These strategies also include the use of smart inhaling devices and systems with built-in AI algorithms. [ABSTRACT FROM AUTHOR]

The treatment for asthma and chronic obstructive pulmonary disease relies on forced inhalation of drug particles. Their distribution is essential for maximizing the outcomes. Patient-specific computational fluid dynamics (CFD) simulations can be used to optimize these therapies. In this regard, this study focuses on creating a parametric model of the human respiratory tract from which synthetic anatomies for particle deposition analysis through CFD simulation could be derived. A baseline geometry up to the fourth generation of bronchioles was extracted from a CT dataset. Radial basis function (RBF) mesh morphing acting on a dedicated tree structure was used to modify this baseline mesh, extracting 1000 synthetic anatomies. A total of 26 geometrical parameters affecting branch lengths, angles, and diameters were controlled. Morphed models underwent CFD simulations to analyze airflow and particle dynamics. Mesh morphing was crucial in generating high-quality computational grids, with 96% of the synthetic database being immediately suitable for accurate CFD simulations. Variations in wall shear stress, particle accretion rate, and turbulent kinetic energy across different anatomies highlighted the impact of the anatomical shape on drug delivery and deposition. The study successfully demonstrates the potential of tree-structure-based RBF mesh morphing in generating parametric airways for drug delivery studies. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Protein‐based therapeutics and vaccines play a pivotal role in the realm of biomedical science. Pulmonary administration offers several advantages including rapid adsorption, non‐invasive, increased local drug concentration, and bypassed first‐pass metabolism, thus holding great potential to address multiple unmet medical needs in lung‐related diseases and vaccination. However, the limited success of inhaled proteins in clinical settings highlights the challenges associated with protein stability and the physiological barriers within the respiratory system. To overcome these hurdles, a variety of delivery systems including polymers, liposomes, cell‐derived membranes, and inorganic materials are developed to improve the stability, mucus penetration, retention time, and bioavailability of proteins. With the outbreak of COVID‐19, the pulmonary administration of proteins has drawn great attention. In this review, the design principle, preparation, biomedical application, progress in clinical translation, advantages, and disadvantages of each kind of delivery system are summarized, with an emphasis on carrier materials.

Abstract Background The understanding of inhaled particle respiratory tract deposition is a key link to understand the health effects of particles or the efficiency for medical drug delivery via the lung. However, there are few experimental data on particle respiratory tract deposition, and the existing data deviates considerably when comparing results for particles > 1 μm. Methods We designed an experimental set-up to measure deposition in the respiratory tract for particles > 1 μm, more specifically 2.3 μm, with careful consideration to minimise foreseen errors. We measured the deposition in seventeen healthy adults (21–68 years). The measurements were performed at tidal breathing, during three consecutive 5-minute periods while logging breathing patterns. Pulmonary function tests were performed, including the new airspace dimension assessment (AiDA) method measuring distal lung airspace radius (r AiDA). The lung characteristics and breathing variables were used in statistical models to investigate to what extent they can explain individual variations in measured deposited particle fraction. The measured particle deposition was compared to values predicted with whole lung models. Model calculations were made for each subject using measured variables as input (e.g., breathing pattern and functional residual capacity). Results The measured fractional deposition for 2.3 μm particles was 0.60 ± 0.14, which is significantly higher than predicted by any of the models tested, ranging from 0.37 ± 0.08 to 0.53 ± 0.09. The multiple-path particle dosimetry (MPPD) model most closely predicted the measured deposition when using the new PNNL lung model. The individual variability in measured particle deposition was best explained by breathing pattern and distal airspace radius (r AiDA) at half inflation from AiDA. All models underestimated inter-subject variability even though the individual breathing pattern and functional residual capacity for each participant was used in the model. Conclusions Whole lung models need to be tuned and improved to predict the respiratory tract particle deposition of micron-sized particles, and to capture individual variations – a variation that is known to be higher for aged and diseased lungs. Further, the results support the hypothesis that the AiDA method measures dimensions in the peripheral lung and that r AiDA, as measured by the AiDA, can be used to better understand the individual variation in the dose to healthy and diseased lungs.

The deposition of fly ash on the heat exchanger will reduce the heat transfer efficiency of the system. This article conducted experiments and simulations on the deposition, exploring the effects of velocity, particle size on the deposition position. In addition, deposition density distribution was demonstrated, the calculation method of fin thermal resistance was improved, and the efficiency of fins was also calculated. The results showed that deposition decreased with velocity increasing, and the simulation results were in good agreement with the experimental results. The deposition distribution of the first section of the fin is unimodal, and the maximum deposition value approaches the peak of the fin. The distribution of the second section of the fin becomes bimodal with increasing velocity. In addition, as the speed increases, due to the decrease in deposition mass, the thermal resistance decreases by 53.2% and the fin efficiency increases by 8.82%.

AbstractThe airflow behaviour and particle deposition before and after the maxillary expansion are evaluated using the computational fluid dynamics method. A pediatric patient was subjected to maxillary expansion and the CT scans of pre and post were recorded. The procured CT scans were developed into 3D models using Materialise MIMICS 21.0 (Materialise, Ann Arbor, MI). The analysis was performed using ANSYS FLUENT 2020 R2 with three different flow rates defined at the nostril inlet as 5, 10, and 15 LPM. The surface area and nasal volume increased by 5.1% and 16.5%, respectively, for the post-maxillary expansion case. The velocity profiles show a maximum value at the nasal valve regions followed by a decreased velocity in the mid-nasal region with an 85% lower velocity observed at the nasal valve for the post-maxillary expansion case. The nasal resistance and pressure drop decrease by 46% to 66% in post-maxillary expansion cases. The maximum WSS at the nasal valve region is observed which is reduced by around 47% for post-maxillary expansion cases. Particle deposition studies show a reduction in particle depositions in post cases indicating a greater number of inhaled particles reaching the lungs. The pressure drop and the nasal resistance values were reduced by more than 50% for post-maxillary expansion. The particle deposition studies show increased depositions at higher flow rates for both cases.

Background: The understanding of inhaled particle respiratory tract deposition is a key link to understand the health effects of particles or the efficiency for medical drug delivery via the lung. However, there are few experimental data on particle respiratory tract deposition, and the existing data deviates considerably when comparing results for particles > 1 μm. Methods: We designed an experimental set-up to measure deposition in the respiratory tract for particles > 1 μm, more specifically 2.3 μm, with careful consideration to minimise foreseen errors. We measured the deposition in seventeen healthy adults (21–68 years). The measurements were performed at tidal breathing, during three consecutive 5-minute periods while logging breathing patterns. Pulmonary function tests were performed, including the new airspace dimension assessment (AiDA) method measuring distal lung airspace radius (rAiDA). The lung characteristics and breathing variables were used in statistical models to investigate to what extent they can explain individual variations in measured deposited particle fraction. The measured particle deposition was compared to values predicted with whole lung models. Model calculations were made for each subject using measured variables as input (e.g., breathing pattern and functional residual capacity). Results: The measured fractional deposition for 2.3 μm particles was 0.60 ± 0.14, which is significantly higher than predicted by any of the models tested, ranging from 0.37 ± 0.08 to 0.53 ± 0.09. The multiple-path particle dosimetry (MPPD) model most closely predicted the measured deposition when using the new PNNL lung model. The individual variability in measured particle deposition was best explained by breathing pattern and distal airspace radius (rAiDA) at half inflation from AiDA. All models underestimated inter-subject variability even though the individual breathing pattern and functional residual capacity for each participant was used in the model. Conclusions: Whole lung models need to be tuned and improved to predict the respiratory tract particle deposition of micron-sized particles, and to capture individual variations – a variation that is known to be higher for aged and diseased lungs. Further, the results support the hypothesis that the AiDA method measures dimensions in the peripheral lung and that rAiDA, as measured by the AiDA, can be used to better understand the individual variation in the dose to healthy and diseased lungs. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Dosimetry models for the estimation of particle deposition in the human respiratory tract (RT) in conjunction with clearance transport models are vital components to relate human exposure with internal dose in a quantitative manner. The current work highlights knowledge and modelling approaches on particle deposition and translocation in the human body in an effort to determine health risks in respect to different particle physicochemical properties and human physiology parameters. These include breathing conditions, variability of the geometry of the RT, chemical composition and size of deposits. Different dosimetry modelling approaches have been studied including empirical formulations, one-dimensional flow modelling and computational fluid dynamic methods (CFD). The importance of a realistic modelling of hygroscopicity has been also investigated. A better understanding of the relationship between health effects and inhaled particle dose may be elaborated using dosimetry and clearance modelling tools. A future required approach is to combine dosimetry models with physiologically based pharmacokinetic models (PBPK) to simulate the transport and cumulative dose of particle-bound chemical species in different organs and tissues of the human body. [ABSTRACT FROM AUTHOR]