Pub Date : 2026-01-29DOI: 10.1016/j.jaerosci.2026.106753
Tian Deng , Xue E. Sheng , Qian H. He , Yi Luo , Xiang Zheng
Mixed aerosols are ubiquitous and play a vital role in production and life, such as chemical and pharmaceutical industries, air pollution study, and so on. Particle size distribution (PSD) and concentration serve as general and critical tools to analyze their chemical and physical properties. However, mixed aerosols are often treated erroneously as one homogeneous aerosol to simplify their measurement, and the characteristic parameters of each elementary aerosol cannot be obtained separately and accurately. In this study, we propose an optical method with a compact set-up to characterize elementary aerosols of binary external mixed aerosol based on the Light Scattering Angular Spectrum (LSAS). PSDs, refractive indexes, and concentrations of each elementary aerosol are decoupled from continuous angular light scattering signals using an improved particle swarm algorithm. A prototype sensor was designed for validation. The laboratory experimental results indicate that the maximum relative error of LSAS between our prototype sensor and reference data is 17.15% and the mean relative error of the inversion result between test aerosol parameters is 4.91%. Our method provides an exceptional ability for real-time and in-situ monitoring of mixed aerosol in industry.
{"title":"An optical sensing method for external mixed aerosol based on light scattering angular spectrum","authors":"Tian Deng , Xue E. Sheng , Qian H. He , Yi Luo , Xiang Zheng","doi":"10.1016/j.jaerosci.2026.106753","DOIUrl":"10.1016/j.jaerosci.2026.106753","url":null,"abstract":"<div><div>Mixed aerosols are ubiquitous and play a vital role in production and life, such as chemical and pharmaceutical industries, air pollution study, and so on. Particle size distribution (PSD) and concentration serve as general and critical tools to analyze their chemical and physical properties. However, mixed aerosols are often treated erroneously as one homogeneous aerosol to simplify their measurement, and the characteristic parameters of each elementary aerosol cannot be obtained separately and accurately. In this study, we propose an optical method with a compact set-up to characterize elementary aerosols of binary external mixed aerosol based on the Light Scattering Angular Spectrum (LSAS). PSDs, refractive indexes, and concentrations of each elementary aerosol are decoupled from continuous angular light scattering signals using an improved particle swarm algorithm. A prototype sensor was designed for validation. The laboratory experimental results indicate that the maximum relative error of LSAS between our prototype sensor and reference data is 17.15% and the mean relative error of the inversion result between test aerosol parameters is 4.91%. Our method provides an exceptional ability for real-time and in-situ monitoring of mixed aerosol in industry.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"193 ","pages":"Article 106753"},"PeriodicalIF":2.9,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-20DOI: 10.1016/j.jaerosci.2026.106752
Ruijin Xie , Mingliang Xie
We report the discovery of a frozen state in shear-induced coagulation of particles within a decaying Taylor-Green vortex, using high-resolution numerical simulation based on the average kernel method. Contrary to the well-established self-similar theory predicting a moment ratio for homogeneous systems, the spatially averaged value stabilizes at approximately under the condition . This frozen state arises because the statistical properties of the moment fields, established during the early vigorous flow stage, become locked in as the flow decays. The coagulation rate diminishes to negligible levels while convective and diffusive transport vanish, preventing the system from reaching the classical homogeneous equilibrium. Our findings reveal a strong history dependence in coagulation dynamics, demonstrating that spatially averaged moment statistics can become path-dependent and remain far from homogeneous equilibrium, even after flow motion ceases. This challenges the common reduction of spatially extended systems to zero-dimensional models and has significant implications for predicting aerosol evolution in decaying turbulence environments.
{"title":"Technical note: Frozen moment ratio and persistent memory in shear-induced coagulation within a decaying vortex","authors":"Ruijin Xie , Mingliang Xie","doi":"10.1016/j.jaerosci.2026.106752","DOIUrl":"10.1016/j.jaerosci.2026.106752","url":null,"abstract":"<div><div>We report the discovery of a frozen state in shear-induced coagulation of particles within a decaying Taylor-Green vortex, using high-resolution numerical simulation based on the average kernel method. Contrary to the well-established self-similar theory predicting a moment ratio <span><math><mrow><msub><mi>M</mi><mi>C</mi></msub><mo>=</mo><mn>2</mn></mrow></math></span> for homogeneous systems, the spatially averaged value <span><math><mrow><mo>⟨</mo><msub><mi>M</mi><mi>C</mi></msub><mo>⟩</mo></mrow></math></span> stabilizes at approximately <span><math><mrow><mn>4.5</mn></mrow></math></span> under the condition <span><math><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mn>10</mn><mo>,</mo><mi>S</mi><mi>c</mi><mo>=</mo><mn>1</mn><mo>,</mo><mi>D</mi><mi>a</mi><mo>=</mo><mn>1</mn></mrow></math></span>. This frozen state arises because the statistical properties of the moment fields, established during the early vigorous flow stage, become locked in as the flow decays. The coagulation rate diminishes to negligible levels <span><math><mrow><mrow><mo>⟨</mo><msub><mi>T</mi><mrow><mi>c</mi><mi>o</mi><mi>a</mi><mi>g</mi></mrow></msub><mo>⟩</mo></mrow><mo>∼</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>9</mn></mrow></msup></mrow></math></span> while convective and diffusive transport vanish, preventing the system from reaching the classical homogeneous equilibrium. Our findings reveal a strong history dependence in coagulation dynamics, demonstrating that spatially averaged moment statistics can become path-dependent and remain far from homogeneous equilibrium, even after flow motion ceases. This challenges the common reduction of spatially extended systems to zero-dimensional models and has significant implications for predicting aerosol evolution in decaying turbulence environments.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"193 ","pages":"Article 106752"},"PeriodicalIF":2.9,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-31DOI: 10.1016/j.jaerosci.2025.106741
Krzysztof M. Markowicz , Piotr Markuszewski , Michał A. Posyniak , Przemysław Makuch , Małgorzata Kitowska , Anna Rozwadowska
This study presents results of a field experiment in the Baltic Sea coastal area focused on optical and microphysical aerosol properties and particle water uptake. This experiment took place in Sopot (Poland) in March 2023. Hygroscopic aerosol properties were measured with two Aurora 4000 nephelometers controlled by the Aerosol Condition System (ACS1000), absorption properties with an aethalometer AE-31, and aerosol size distribution with SMPS/OPS devices. Due to the variability of weather conditions, different aerosol properties were observed, including relatively clean marine air mass with sea spray as well as local and long-range transported pollution. Hygroscopic properties defined by the scattering enhancement factor f(RH) at 85 % of relative humidity (RH) and kappa parameters show elevated values not only during marine air masses but also during the transport of continental air masses from the south-western direction. Statistically significant Pearson correlation coefficients were found for relations between sulphate aerosol proportion in aerosol mass (from MERRA-2 reanalysis) and both hygroscopicity parameters, f(RH = 85 %) and kappa (0.47 and 0.54, respectively).
Experiment closure shows that the aerosol scattering coefficient obtained from numerical simulation based on aerosol size distribution from observations and refractive index estimated from MERRA-2 reanalysis agree with Aurora 4000 measurements. In the case of the aerosol absorption coefficient, the comparison with aethalometer observation is not so consistent due to the high sensitivity of this parameter to the assumed value of the imaginary part of the refractive index.
{"title":"Aerosol microphysical and optical closure study in the Baltic Sea coastal zone","authors":"Krzysztof M. Markowicz , Piotr Markuszewski , Michał A. Posyniak , Przemysław Makuch , Małgorzata Kitowska , Anna Rozwadowska","doi":"10.1016/j.jaerosci.2025.106741","DOIUrl":"10.1016/j.jaerosci.2025.106741","url":null,"abstract":"<div><div>This study presents results of a field experiment in the Baltic Sea coastal area focused on optical and microphysical aerosol properties and particle water uptake. This experiment took place in Sopot (Poland) in March 2023. Hygroscopic aerosol properties were measured with two Aurora 4000 nephelometers controlled by the Aerosol Condition System (ACS1000), absorption properties with an aethalometer AE-31, and aerosol size distribution with SMPS/OPS devices. Due to the variability of weather conditions, different aerosol properties were observed, including relatively clean marine air mass with sea spray as well as local and long-range transported pollution. Hygroscopic properties defined by the scattering enhancement factor <em>f</em>(RH) at 85 % of relative humidity (RH) and kappa parameters show elevated values not only during marine air masses but also during the transport of continental air masses from the south-western direction. Statistically significant Pearson correlation coefficients were found for relations between sulphate aerosol proportion in aerosol mass (from MERRA-2 reanalysis) and both hygroscopicity parameters, <em>f</em>(RH = 85 %) and kappa (0.47 and 0.54, respectively).</div><div>Experiment closure shows that the aerosol scattering coefficient obtained from numerical simulation based on aerosol size distribution from observations and refractive index estimated from MERRA-2 reanalysis agree with Aurora 4000 measurements. In the case of the aerosol absorption coefficient, the comparison with aethalometer observation is not so consistent due to the high sensitivity of this parameter to the assumed value of the imaginary part of the refractive index.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"193 ","pages":"Article 106741"},"PeriodicalIF":2.9,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145903811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-27DOI: 10.1016/j.jaerosci.2025.106735
Patrick Warfield-McAlpine , David F. Fletcher , Kiao Inthavong
Turbulent particle dispersion in wall-bounded flows plays a critical role in a range of industrial and biomedical applications, including respiratory drug delivery and inhalation toxicology. This study investigates the performance of a hybrid Stress-Blended Eddy Simulation (SBES) turbulence model coupled with the Discrete Random Walk (DRW) particle dispersion model to predict particle transport and deposition in simple cylindrical and complex anatomical geometries. Simulations were conducted using CFD for three configurations: a vertical tube, a 90° pipe bend, and a realistic human nasal airway, under fully turbulent conditions (Re = 10,000) and two inhalation flow rates (30 and 60 L/min).
The SBES model provided improved resolution of turbulent structures and consistent agreement with experimental correlations for particle deposition in all geometries. In the vertical tube where particle deposition is driven by turbulence dispersion, the – SST model coupled with the Low-Reynolds Number (LRN) correction provided the most accurate results. However, in the pipe bend and nasal cavity, where deposition was dominated by inertial impaction, sensitivity to the LRN correction was reduced. For nasal airflow simulations, the SBES model with or without the LRN correction produced accurate deposition trends across all particle sizes and flow rates.
Results underscore that model selection should be tailored to the dominant deposition mechanism, turbulence-driven or inertia-driven. Whilst the SBES model with the LRN correction offered the most consistent performance in resolving turbulent dispersion for all three cases, the standard – SST model with LRN correction was more accurate for turbulence driven deposition.
Future work should evaluate additional dispersion models such as the Continuous Random Walk (CRW) to further improve physical realism in particle transport simulations. This study reinforces the value of the SBES model in simulating complex, aerosol behaviour in respiratory applications.
{"title":"Assessment of turbulent particle dispersion in the respiratory airway using a hybrid RANS-LES model","authors":"Patrick Warfield-McAlpine , David F. Fletcher , Kiao Inthavong","doi":"10.1016/j.jaerosci.2025.106735","DOIUrl":"10.1016/j.jaerosci.2025.106735","url":null,"abstract":"<div><div>Turbulent particle dispersion in wall-bounded flows plays a critical role in a range of industrial and biomedical applications, including respiratory drug delivery and inhalation toxicology. This study investigates the performance of a hybrid Stress-Blended Eddy Simulation (SBES) turbulence model coupled with the Discrete Random Walk (DRW) particle dispersion model to predict particle transport and deposition in simple cylindrical and complex anatomical geometries. Simulations were conducted using CFD for three configurations: a vertical tube, a 90° pipe bend, and a realistic human nasal airway, under fully turbulent conditions (Re = 10,000) and two inhalation flow rates (30 and 60 L/min).</div><div>The SBES model provided improved resolution of turbulent structures and consistent agreement with experimental correlations for particle deposition in all geometries. In the vertical tube where particle deposition is driven by turbulence dispersion, the <span><math><mi>k</mi></math></span>–<span><math><mi>ω</mi></math></span> SST model coupled with the Low-Reynolds Number (LRN) correction provided the most accurate results. However, in the <span><math><mrow><mn>90</mn><mo>°</mo></mrow></math></span> pipe bend and nasal cavity, where deposition was dominated by inertial impaction, sensitivity to the LRN correction was reduced. For nasal airflow simulations, the SBES model with or without the LRN correction produced accurate deposition trends across all particle sizes and flow rates.</div><div>Results underscore that model selection should be tailored to the dominant deposition mechanism, turbulence-driven or inertia-driven. Whilst the SBES model with the LRN correction offered the most consistent performance in resolving turbulent dispersion for all three cases, the standard <span><math><mi>k</mi></math></span>–<span><math><mi>ω</mi></math></span> SST model with LRN correction was more accurate for turbulence driven deposition.</div><div>Future work should evaluate additional dispersion models such as the Continuous Random Walk (CRW) to further improve physical realism in particle transport simulations. This study reinforces the value of the SBES model in simulating complex, aerosol behaviour in respiratory applications.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"192 ","pages":"Article 106735"},"PeriodicalIF":2.9,"publicationDate":"2025-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-22DOI: 10.1016/j.jaerosci.2025.106740
Ming-Ze Sun, Hong-Wei Li, Ji-Ning Sun
The aerosol dynamics in wet flue-gas cooling towers under crosswind conditions are highly complex. Traditional models are inadequate for accurately predicting aerosol dynamics of solid particles under high humidity and turbulent conditions. In this study, an aerosol dynamics model was established by combining the Finite Volume Method (FVM) with the Taylor Expansion Method of Moments (TEMOM). The effects of condensation, coagulation, and fragmentation on the geometric mean diameter (GMD) and particle number concentration (PNC) under different Beaufort wind scales (Bft) were investigated, and the aerosol variations during the growth, transport, and deposition were revealed. The results showed that during aerosol growth, the dominant dynamic process shifted from condensation to coagulation as Bft increased from 2 to 5. Under low Bft (2–3), 22 %–58 % of the outlet area was compressed by upper leeward-side vortices, whereas high Bft (4–5) suppressed these vortices and promoted coagulation in the leeward side. During aerosol transport, the upward motion was sustained by the outward-rotating vortex pairs. Aerosols were driven into translation and rotation by large-scale vortices under low Bft, and fragmentation was enhanced by small-scale vortices under high Bft. During aerosol deposition, inward-rotating vortex pairs were decomposed into small-scale turbulent vortices, thereby expanding the deposition width by a factor of 2.17. Aerosols entrained by the penetrating flow at the tower bottom were deposited in the near field, while aerosols from higher altitudes were carried by the descending airflow and deposited in the far field. The findings provided a basis for accurately predicting aerosol dispersion and deposition.
{"title":"Simulation and experimental verification of multi-process aerosol dynamics evolution in the wet flue gas cooling towers under crosswind conditions using FVM-TEMOM","authors":"Ming-Ze Sun, Hong-Wei Li, Ji-Ning Sun","doi":"10.1016/j.jaerosci.2025.106740","DOIUrl":"10.1016/j.jaerosci.2025.106740","url":null,"abstract":"<div><div>The aerosol dynamics in wet flue-gas cooling towers under crosswind conditions are highly complex. Traditional models are inadequate for accurately predicting aerosol dynamics of solid particles under high humidity and turbulent conditions. In this study, an aerosol dynamics model was established by combining the Finite Volume Method (FVM) with the Taylor Expansion Method of Moments (TEMOM). The effects of condensation, coagulation, and fragmentation on the geometric mean diameter (GMD) and particle number concentration (PNC) under different Beaufort wind scales (Bft) were investigated, and the aerosol variations during the growth, transport, and deposition were revealed. The results showed that during aerosol growth, the dominant dynamic process shifted from condensation to coagulation as Bft increased from 2 to 5. Under low Bft (2–3), 22 %–58 % of the outlet area was compressed by upper leeward-side vortices, whereas high Bft (4–5) suppressed these vortices and promoted coagulation in the leeward side. During aerosol transport, the upward motion was sustained by the outward-rotating vortex pairs. Aerosols were driven into translation and rotation by large-scale vortices under low Bft, and fragmentation was enhanced by small-scale vortices under high Bft. During aerosol deposition, inward-rotating vortex pairs were decomposed into small-scale turbulent vortices, thereby expanding the deposition width by a factor of 2.17. Aerosols entrained by the penetrating flow at the tower bottom were deposited in the near field, while aerosols from higher altitudes were carried by the descending airflow and deposited in the far field. The findings provided a basis for accurately predicting aerosol dispersion and deposition.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"192 ","pages":"Article 106740"},"PeriodicalIF":2.9,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-18DOI: 10.1016/j.jaerosci.2025.106739
Francesca Orsola Alfano, Francesco Paolo Di Maio, Alberto Di Renzo
An ideal Dry Powder Inhaler (DPI) would deliver 100 % of the active pharmaceutical ingredient (API) in a fully aerosolized form, regardless of the lung capacity of the patient. In this work, the influence of the instantaneous inhalation flowrate profile on a swirl-based DPI performance is investigated using high-fidelity CFD-DEM simulations of the carrier-API deaggregation, carried out with a customized open-source code specifically optimized for aerosol–particle interaction studies. The study compares four inhalation profiles: an idealized step profile, a realistic inhalation profile for an asthmatic patient, and two ramp profiles that reach the same peak flowrate (PIFR) of 60 L/min as the step profile but with different flow increase rates (FIR): 8.0 L/s2 for Ramp-1 and 3.9 L/s2 for Ramp-2. Both powder emission and API deaggregation are analysed to assess the impact of the initial transient phase, showing that deaggregation of the carrier and emission of the API is delayed by over 50 ms in the ramp profiles, and that the fine particle fraction (FPF) decreases by almost 11 % for the less steep ramp. These results highlight that, despite identical PIFR, FIR critically influences DPI efficiency, affecting both API deaggregation and carrier recovery.
{"title":"Transient flow effects in DPI: A computational study linking inhalation dynamics to performance","authors":"Francesca Orsola Alfano, Francesco Paolo Di Maio, Alberto Di Renzo","doi":"10.1016/j.jaerosci.2025.106739","DOIUrl":"10.1016/j.jaerosci.2025.106739","url":null,"abstract":"<div><div>An ideal Dry Powder Inhaler (DPI) would deliver 100 % of the active pharmaceutical ingredient (API) in a fully aerosolized form, regardless of the lung capacity of the patient. In this work, the influence of the instantaneous inhalation flowrate profile on a swirl-based DPI performance is investigated using high-fidelity CFD-DEM simulations of the carrier-API deaggregation, carried out with a customized open-source code specifically optimized for aerosol–particle interaction studies. The study compares four inhalation profiles: an idealized step profile, a realistic inhalation profile for an asthmatic patient, and two ramp profiles that reach the same peak flowrate (PIFR) of 60 L/min as the step profile but with different flow increase rates (FIR): 8.0 L/s<sup>2</sup> for Ramp-1 and 3.9 L/s<sup>2</sup> for Ramp-2. Both powder emission and API deaggregation are analysed to assess the impact of the initial transient phase, showing that deaggregation of the carrier and emission of the API is delayed by over 50 ms in the ramp profiles, and that the fine particle fraction (FPF) decreases by almost 11 % for the less steep ramp. These results highlight that, despite identical PIFR, FIR critically influences DPI efficiency, affecting both API deaggregation and carrier recovery.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"192 ","pages":"Article 106739"},"PeriodicalIF":2.9,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1016/j.jaerosci.2025.106737
M. Alonso , F.J. Alguacil , J.P. Borra
The critical Peclet number above which particle axial diffusion is negligible has been determined for aerosols in a laminar flow tube. Two theoretical methods have been used: the numerical solution of the advection-diffusion equation (ADE), and a Monte Carlo (MC) simulation of particle trajectory. Two limiting velocity profiles have been considered for the fluid flow, namely, plug flow (uniform flow, UF) and fully developed flow (parabolic, PF). Two flow-related aerosol properties, particle penetration through the tube and its residence time distribution (RTD), have been studied. Three cases can be distinguished. (1) When there is no diffusion, penetration is one, and the dimensionless particle mean residence time is also one, the same as that of the fluid in either UF or PF. (2) When diffusion occurs only in the radial direction, penetration is less than one and decreases as the dimensionless particle diffusion coefficient increases; the mean particle residence time is also equal to one in UF but can be much less than one in PF so that, on average, particles in PF spend less time in the tube than the fluid, in spite that no external force is acting upon them. However, no particle can leave the tube in a dimensionless time shorter than 1/2. (3) When radial and axial diffusion are both important, penetration is still smaller than one, but larger than in case (2); the mean residence time in UF or PF is smaller than that of the fluid and, in contrast with case (2), it can be even smaller than 1/2 in PF. The critical value of the Peclet number depends on the specific flow-related aerosol property under consideration. Thus, axial diffusion does not affect particle penetration for Peclet larger than 10–20, and does not affect the mean aerosol residence time for Peclet larger than about 50; but the residence time distribution of the particles is affected by axial diffusion at values of Peclet as large as 6000. The mean aerosol residence time depends on its diffusion coefficient and on the tube aspect ratio (radius/length). Two practical correlations, one for UF and the other for PF, have been developed. Each correlation is the product of two factors which account separately for the contributions of radial and axial diffusion.
{"title":"The role of the Peclet number in the diffusion process of aerosols in a tube and correlations to estimate the mean particle residence time","authors":"M. Alonso , F.J. Alguacil , J.P. Borra","doi":"10.1016/j.jaerosci.2025.106737","DOIUrl":"10.1016/j.jaerosci.2025.106737","url":null,"abstract":"<div><div>The critical Peclet number above which particle axial diffusion is negligible has been determined for aerosols in a laminar flow tube. Two theoretical methods have been used: the numerical solution of the advection-diffusion equation (ADE), and a Monte Carlo (MC) simulation of particle trajectory. Two limiting velocity profiles have been considered for the fluid flow, namely, plug flow (uniform flow, UF) and fully developed flow (parabolic, PF). Two flow-related aerosol properties, particle penetration through the tube and its residence time distribution (RTD), have been studied. Three cases can be distinguished. (1) When there is no diffusion, penetration is one, and the dimensionless particle mean residence time is also one, the same as that of the fluid in either UF or PF. (2) When diffusion occurs only in the radial direction, penetration is less than one and decreases as the dimensionless particle diffusion coefficient increases; the mean particle residence time is also equal to one in UF but can be much less than one in PF so that, on average, particles in PF spend less time in the tube than the fluid, in spite that no external force is acting upon them. However, no particle can leave the tube in a dimensionless time shorter than 1/2. (3) When radial and axial diffusion are both important, penetration is still smaller than one, but larger than in case (2); the mean residence time in UF or PF is smaller than that of the fluid and, in contrast with case (2), it can be even smaller than 1/2 in PF. The critical value of the Peclet number depends on the specific flow-related aerosol property under consideration. Thus, axial diffusion does not affect particle penetration for Peclet larger than 10–20, and does not affect the mean aerosol residence time for Peclet larger than about 50; but the residence time distribution of the particles is affected by axial diffusion at values of Peclet as large as 6000. The mean aerosol residence time depends on its diffusion coefficient and on the tube aspect ratio (radius/length). Two practical correlations, one for UF and the other for PF, have been developed. Each correlation is the product of two factors which account separately for the contributions of radial and axial diffusion.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"192 ","pages":"Article 106737"},"PeriodicalIF":2.9,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145788517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1016/j.jaerosci.2025.106738
Nicolás Amigo, Neyling Macalopú
Molecular dynamics simulations were employed to study the impact behavior of amorphous Si nanoparticles on a crystalline Si substrate at velocities in the range of 0.5 and 4.0 km/s and particle sizes from 5 to 13 nm. The simulations revealed three distinct regimes depending on impact conditions: adhesion, rebound, and disintegration. At low velocities, nanoparticles adhered with limited deformation, suggesting favorable conditions for deposition, whereas intermediate velocities induced strong elastic deformation in the substrate that promoted rebound, particularly for larger nanoparticles. At the highest velocities, extensive fragmentation and disintegration occurred, ejecting material and generating debris. Plastic activity analysis revealed that both impact velocity and particle size strongly influenced crater morphology, substrate deformation, and nanoparticle fragmentation, with larger diameters enhancing these effects due to their higher total kinetic energy. Deformation was mostly confined to the impact region, with shear strain and dislocations concentrated at the particle–substrate interface. These results provide insights into cold spray deposition and nanoscale surface engineering in amorphous-crystalline systems.
{"title":"Insights into amorphous silicon nanoparticle impacts on crystalline silicon through molecular dynamics","authors":"Nicolás Amigo, Neyling Macalopú","doi":"10.1016/j.jaerosci.2025.106738","DOIUrl":"10.1016/j.jaerosci.2025.106738","url":null,"abstract":"<div><div>Molecular dynamics simulations were employed to study the impact behavior of amorphous Si nanoparticles on a crystalline Si substrate at velocities in the range of 0.5 and 4.0 km/s and particle sizes from 5 to 13 nm. The simulations revealed three distinct regimes depending on impact conditions: adhesion, rebound, and disintegration. At low velocities, nanoparticles adhered with limited deformation, suggesting favorable conditions for deposition, whereas intermediate velocities induced strong elastic deformation in the substrate that promoted rebound, particularly for larger nanoparticles. At the highest velocities, extensive fragmentation and disintegration occurred, ejecting material and generating debris. Plastic activity analysis revealed that both impact velocity and particle size strongly influenced crater morphology, substrate deformation, and nanoparticle fragmentation, with larger diameters enhancing these effects due to their higher total kinetic energy. Deformation was mostly confined to the impact region, with shear strain and dislocations concentrated at the particle–substrate interface. These results provide insights into cold spray deposition and nanoscale surface engineering in amorphous-crystalline systems.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"192 ","pages":"Article 106738"},"PeriodicalIF":2.9,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145788518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-12DOI: 10.1016/j.jaerosci.2025.106736
Guangze Li , Zhenzhong Zhang , Liuyong Chang , Ragui Karim , Yiwei Zhao , Boxuan Cui , Longfei Chen , Ye Kang , Lei He
Aviation-emitted soot particles have a significant impact on the global radiation balance and climate change. The emission of these particles around airports poses a serious health risk to surrounding residents. This risk is particularly accentuated when aircraft engines are operating at ground idle and takeoff status during which soot particle emissions are substantially elevated. Consequently, the importance of researching aviation soot particle emissions becomes increasingly evident. The present study investigates the center-staged lean-burn low-emission combustor of a commercial turbofan engine. The impacts of varying different equivalence ratios on the nanostructure, micro-morphology of soot particles during the engine ground idle and takeoff status were analyzed with a combined micro/macro characterization technique. The results indicate that during takeoff conditions, a higher equivalence ratio results in increased graphitization degree of soot particles and fringe length, as well as decreased fringe tortuosity, amorphous carbon content, and oxidation. An increase in the equivalence ratio results in the opposite trends under the ground idle condition. The soot particles during ground idle exhibit lower graphitization compared to takeoff, with the proportion of fringe lengths below 1.5 nm decreasing by approximately 4 %. In contrast, the proportion of fringe tortuosity above 1.5 increases by 6 %. Additionally, the average particle number concentration increases dramatically, rising from 1.9E4 #/cm3 to 1.1E7 #/cm3. This study provides essential data for optimizing the design of aviation engine combustors and mitigating soot emissions, offering significant implications for improving environmental quality in airport areas.
{"title":"Impact of equivalence ratio on soot emissions from turbofan combustor during takeoff and ground idle status","authors":"Guangze Li , Zhenzhong Zhang , Liuyong Chang , Ragui Karim , Yiwei Zhao , Boxuan Cui , Longfei Chen , Ye Kang , Lei He","doi":"10.1016/j.jaerosci.2025.106736","DOIUrl":"10.1016/j.jaerosci.2025.106736","url":null,"abstract":"<div><div>Aviation-emitted soot particles have a significant impact on the global radiation balance and climate change. The emission of these particles around airports poses a serious health risk to surrounding residents. This risk is particularly accentuated when aircraft engines are operating at ground idle and takeoff status during which soot particle emissions are substantially elevated. Consequently, the importance of researching aviation soot particle emissions becomes increasingly evident. The present study investigates the center-staged lean-burn low-emission combustor of a commercial turbofan engine. The impacts of varying different equivalence ratios on the nanostructure, micro-morphology of soot particles during the engine ground idle and takeoff status were analyzed with a combined micro/macro characterization technique. The results indicate that during takeoff conditions, a higher equivalence ratio results in increased graphitization degree of soot particles and fringe length, as well as decreased fringe tortuosity, amorphous carbon content, and oxidation. An increase in the equivalence ratio results in the opposite trends under the ground idle condition. The soot particles during ground idle exhibit lower graphitization compared to takeoff, with the proportion of fringe lengths below 1.5 nm decreasing by approximately 4 %. In contrast, the proportion of fringe tortuosity above 1.5 increases by 6 %. Additionally, the average particle number concentration increases dramatically, rising from 1.9E4 #/cm<sup>3</sup> to 1.1E7 #/cm<sup>3</sup>. This study provides essential data for optimizing the design of aviation engine combustors and mitigating soot emissions, offering significant implications for improving environmental quality in airport areas.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"192 ","pages":"Article 106736"},"PeriodicalIF":2.9,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-11DOI: 10.1016/j.jaerosci.2025.106733
Liyang Zhang , Jiacun Wu , Zihao Feng , Kaiyue Wu , Yutai Li , Haiyun Luo , Xiaole Zhang , Yangyang Fu
Dielectric barrier discharge (DBD) plasma is an emerging and promising technique for air disinfection. However, the charging mechanisms and dynamics of flowing bioaerosols interacting with transient streamer discharges remain poorly understood. In this study, a coupled model was developed to simulate the interactions of a flowing bacterial particle with a single-filament DBD. The model integrates a plasma model, a fluid flow model, and an aerosol dynamic model. The impacts of airflow velocity, voltage frequency, particle size, and particle permittivity were examined. Spatial analysis reveals that the effective particle charging region extends up to ∼20 times the filament size (∼50 μm). Bipolar charging was observed due to distinct electron and positive ion distributions in DBD. Most of the domain (Region II) exhibits positive charging dominated by expanded positive ions, while electron charging plays a significant role within the plasma region (Region I). For a 1-μm particle, the steady-state charge ranges from −350 to +450 elementary charges (e). In Region II, the steady-state charging is proportional to the square of its diameter (dp2) due to the field charging of positive ions. However, in Region I, the charge value deviates from this proportionality due to the significant contributions of electron thermal motion and drift flux. Increasing particle relative permittivity (4–80) predominantly enhances charging in Region II (up to ∼500 e), which is attributed to dielectric polarization and the increasing positive-ion drift flux. Regarding aerosol dynamics, the surface-charge-induced electric field was found to have a critical influence on the particle trajectory. Under low-frequency (<300 Hz) and/or low-velocity (<2 m/s), particles exhibit unique behaviors like surface trapping, vortex-shaped/helical trajectories, and compressed motion. Additionally, increasing the particle size can significantly enhance surface trapping and vortical oscillation, while permittivity exerts a limited influence. These findings can provide insights into the mechanisms of plasma-aerosol interactions and offer guidance for optimizing plasma-based air disinfection and particle manipulation systems.
{"title":"Simulation on charging and dynamics of a flowing bacterial aerosol in parallel-rod dielectric barrier discharge","authors":"Liyang Zhang , Jiacun Wu , Zihao Feng , Kaiyue Wu , Yutai Li , Haiyun Luo , Xiaole Zhang , Yangyang Fu","doi":"10.1016/j.jaerosci.2025.106733","DOIUrl":"10.1016/j.jaerosci.2025.106733","url":null,"abstract":"<div><div>Dielectric barrier discharge (DBD) plasma is an emerging and promising technique for air disinfection. However, the charging mechanisms and dynamics of flowing bioaerosols interacting with transient streamer discharges remain poorly understood. In this study, a coupled model was developed to simulate the interactions of a flowing bacterial particle with a single-filament DBD. The model integrates a plasma model, a fluid flow model, and an aerosol dynamic model. The impacts of airflow velocity, voltage frequency, particle size, and particle permittivity were examined. Spatial analysis reveals that the effective particle charging region extends up to ∼20 times the filament size (∼50 μm). Bipolar charging was observed due to distinct electron and positive ion distributions in DBD. Most of the domain (Region II) exhibits positive charging dominated by expanded positive ions, while electron charging plays a significant role within the plasma region (Region I). For a 1-μm particle, the steady-state charge ranges from −350 to +450 elementary charges (e). In Region II, the steady-state charging is proportional to the square of its diameter (<em>d</em><sub>p</sub><sup>2</sup>) due to the field charging of positive ions. However, in Region I, the charge value deviates from this proportionality due to the significant contributions of electron thermal motion and drift flux. Increasing particle relative permittivity (4–80) predominantly enhances charging in Region II (up to ∼500 e), which is attributed to dielectric polarization and the increasing positive-ion drift flux. Regarding aerosol dynamics, the surface-charge-induced electric field was found to have a critical influence on the particle trajectory. Under low-frequency (<300 Hz) and/or low-velocity (<2 m/s), particles exhibit unique behaviors like surface trapping, vortex-shaped/helical trajectories, and compressed motion. Additionally, increasing the particle size can significantly enhance surface trapping and vortical oscillation, while permittivity exerts a limited influence. These findings can provide insights into the mechanisms of plasma-aerosol interactions and offer guidance for optimizing plasma-based air disinfection and particle manipulation systems.</div></div>","PeriodicalId":14880,"journal":{"name":"Journal of Aerosol Science","volume":"192 ","pages":"Article 106733"},"PeriodicalIF":2.9,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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