Special Issue "Levitating Droplet Clusters in Aerosol Science"

A special issue of Atmosphere (ISSN 2073-4433). This special issue belongs to the section "Aerosols".

Deadline for manuscript submissions: closed (23 April 2021).

Special Issue Editors

Prof. Dr. Alexander A. Fedorets
E-Mail Website
Guest Editor
Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, 625003 Tyumen, Russia
Interests: droplet cluster; microhydrodynamics; microfluidics; heat transfer
Dr. Leonid A. Dombrovsky
E-Mail Website
Guest Editor
Joint Institute for High Temperatures of the Russian Academy of Sciences, 111116 Moscow, Russia
Interests: heat transfer; disperse systems; radiative transfer; droplets
Prof. Dr. Michael J. Nosonovsky
E-Mail Website
Guest Editor
Department of Mechanical Engineering,College of Engineering & Applied Science University of Wisconsin-Milwaukee Milwaukee, WI 53211-0413, Milwaukee, WI 53201-0413, USA
Interests: wetting; friction; surface science; capillary phenomena; droplets
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Edward Bormashenko
E-Mail Website
Guest Editor
Chemical Engineering Department, Engineering Sciences Faculty, Ariel University, Ariel 407000, Israel
Interests: materials science; interface science; metamaterials; foundations of thermodynamics; plasma science
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Self-assembled clusters of levitating condensed microdroplets are a relatively new phenomenon, first described in the literature in 2004. After the discovery of the droplet cluster, intensive studies of this phenomenon have been conducted. These studies resulted in new insights on the mechanisms which control the parameters of the clusters and their evolution. Technologies have been developed to generate clusters with any desirable number of droplets, to stabilize the cluster for a long periods of time, to control the size of individual droplets, and to obtain clusters at relatively low temperatures, which makes them an appropriate platform for the in situ observation of biological processes and as chemical micro-reactors. New phenomena have been observed, such as the chain cluster and hierarchical cluster, electrostatic effects in clusters, as well as unusual symmetries of small clusters. The relationship of clusters to other phenomena, such as breath figures, the Leidenfrost effect, networks, and colloidal clusters, have also been investigated. This Special Issue will cover all topics related to the droplet cluster and other similar phenomena, including:

  • The observation and characterization of droplet clusters;
  • The application of droplet clusters for biological, chemical, and physical experiments;
  • Atmospheric phenomena related to droplet clustering (mist, fog, and clouds);
  • Microfluidic aspects of microdroplet clusters;
  • Relationship of the droplet cluster to the Leidenfrost effect, breath figures, and colloidal clusters;   
  • Methods of droplet cluster characterization and related concepts (entropy, symmetry, etc.).

Prof. Dr. Alexander A. Fedorets
Dr. Leonid A. Dombrovsky
Prof. Michael J. Nosonovsky
Prof. Dr. Edward Bormashenko
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • droplet clusters
  • microdroplets
  • colloidal crystals
  • self-organization

Published Papers (3 papers)

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Research

Communication
Particle Shape Impact on the Radiative Forcing Efficiency Estimated from Single Levitated (NH4)2SO4 Particles
Atmosphere 2021, 12(9), 1231; https://doi.org/10.3390/atmos12091231 - 21 Sep 2021
Viewed by 542
Abstract
Levitation of single trapped particles enables the exploration of fundamental physicochemical aerosol properties never previously achieved. Experimental measurements showed that (NH4)2SO4’s particle shape deviated from sphericity during the crystallization process. Despite that, salt aerosols are assumed to [...] Read more.
Levitation of single trapped particles enables the exploration of fundamental physicochemical aerosol properties never previously achieved. Experimental measurements showed that (NH4)2SO4’s particle shape deviated from sphericity during the crystallization process. Despite that, salt aerosols are assumed to be spheres even in low relative humidity (RH) in most climate models. In the analysis performed here, Mie and T-Matrix codes were operated to simulate crucial parameters needed to estimate the radiative forcing efficiency: extinction efficiency, asymmetry parameter and backscattering fraction. The incorporation of non-spherical effects in (NH4)2SO4 particles can cause a difference of up to 46% radiative forcing efficiency compared to the assumption of sphericity in the 0.3–0.6 µm particle radius range. Full article
(This article belongs to the Special Issue Levitating Droplet Clusters in Aerosol Science)
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Article
Metastable States of Water Aerosols: Comparison by Experiment
Atmosphere 2021, 12(4), 486; https://doi.org/10.3390/atmos12040486 - 12 Apr 2021
Viewed by 480
Abstract
Free energy of water aerosol plasma was calculated using the Debye–Hückel method. It was established that free energies of droplets, ions and simultaneously of all charged particles had local minima (metastable states) at certain concentrations and charges of particles. The calculation results were [...] Read more.
Free energy of water aerosol plasma was calculated using the Debye–Hückel method. It was established that free energies of droplets, ions and simultaneously of all charged particles had local minima (metastable states) at certain concentrations and charges of particles. The calculation results were confirmed by experimental data taken from the literature on a droplet cluster in water vapor and droplet structures in water fog. The possible connection of metastable states with the phenomenon of drop coalescence and rain formation in real clouds, as well as with the generation of stable spatially arranged drop structures, has been indicated. Full article
(This article belongs to the Special Issue Levitating Droplet Clusters in Aerosol Science)
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Article
Modeling Evaporation of Water Droplets as Applied to Survival of Airborne Viruses
Atmosphere 2020, 11(9), 965; https://doi.org/10.3390/atmos11090965 - 10 Sep 2020
Cited by 11 | Viewed by 1920
Abstract
Many viruses, such as coronaviruses, tend to spread airborne inside water microdroplets. Evaporation of the microdroplets may result in a reduction of their contagiousness. However, the evaporation of small droplets is a complex process involving mass and heat transfer, diffusion, convection and solar [...] Read more.
Many viruses, such as coronaviruses, tend to spread airborne inside water microdroplets. Evaporation of the microdroplets may result in a reduction of their contagiousness. However, the evaporation of small droplets is a complex process involving mass and heat transfer, diffusion, convection and solar radiation absorption. Virological studies indicate that airborne virus survival is very sensitive to air humidity and temperature. We employ a model of droplet evaporation with the account for the Knudsen layer. This model suggests that evaporation is sensitive to both temperature and the relative humidity (RH) of the ambient air. We also discuss various mechanisms such as the effect of solar irradiation, the dynamic relaxation of moving droplets in ambient air and the gravitational sedimentation of the droplets. The maximum estimate for the spectral radiative flux in the case of cloudless sky showed that the radiation contribution to evaporation of single water droplets is insignificant. We conclude that at small and even at moderately high levels of RH, microdroplets evaporate within dozens of seconds with the convective heat flux from the air being the dominant mechanism in every case. The numerical results obtained in the paper are in good qualitative agreement with both the published laboratory experiments and seasonal nature of many viral infections. Sophisticated experimental techniques may be needed for in situ observation of interaction of viruses with organic particles and living cells within microdroplets. The novel controlled droplet cluster technology is suggested as a promising candidate for such experimental methodology. Full article
(This article belongs to the Special Issue Levitating Droplet Clusters in Aerosol Science)
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