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Artykuły w czasopismach na temat "Droplets"
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Xu, Jinzhu, Li Jia, Chao Dang, Xinyuan Liu i Yi Ding. "Effects of solid–liquid interaction and mixture concentration on wettability of nano-droplets: Molecular dynamics simulations". AIP Advances 12, nr 10 (1.10.2022): 105313. http://dx.doi.org/10.1063/5.0120656.
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The wetting of droplets plays a critical role in engineering applications. Intensive study on nano-droplets is of great significance in revealing the wetting characteristics of droplets. The wetting behavior of ethanol/water mixture nano-droplets on a smooth substrate was investigated through molecular dynamics simulation in this paper. Five nano-droplets of the ethanol/water mixture with different mass fractions placed on a copper surface with different surface energies were simulated to equilibrium at 298.15 K. The contract angle, wetting limit (the minimum and the maximum surface tension of droplets make the surface completely wetted or completely non-wetted by the droplet), and density distribution at the solid–liquid interface of the nano-droplet were analyzed. The effects of ethanol concentration and solid–liquid interaction (corresponding to the droplet’s surface tension and the substrate’s surface energy, respectively) on droplet wettability were intensely discussed. Results revealed that the contact angle of nano-droplets decreased with the increase in ethanol concentration and the interaction between droplets and the substrate. In addition, the critical and ultimate surface tension increased with the increase in the substrate surface energy. The peak density values of the droplets were proportional to the interaction between the droplets and substrate and not related to the droplet concentration. The research also indicated that solid substrates with different surface energies and droplets with various components affected the contact angle of droplets in different ways: the former not only increased the surface tension of droplets at the solid–liquid interface but also increased the separation energy of solids and droplets, while the latter only had a great influence on the surface tension of droplets at the solid–liquid interface.
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Choi, Woorak, i Sungchan Yun. "Behavior of Compound Materials on Superhydrophobic Cylinders: Effects of Droplet’s Size and Interface Angle". Korean Journal of Metals and Materials 62, nr 3 (5.03.2024): 222–28. http://dx.doi.org/10.3365/kjmm.2024.62.3.222.
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Compound droplets can consist of two or more immiscible substances sharing an interface. Among such droplets, the low-viscosity component of Janus droplets can exhibit peculiar bouncing behavior on nonwettable surfaces. There have been recent advances in droplet control technologies, however the impact dynamics of droplets on complex surfaces, and strategies to control their behavior, have not been extensively studied. This study employs the volume of fluid method to analyze the effects of Janus droplet size and the initial interface angle on the dynamics of the two fluidic components in droplets on superhydrophobic cylinders. Janus droplets are composed of low-viscosity (W-) and high-viscosity liquid (G-component). The dynamic characteristics of Janus droplets are investigated as a function of Weber number (<i>We</i>), initial interface angle, the ratio of the droplet’s diameter to the cylinder’s diameter, and viscosity ratio (α). Numerical models provide a regime map of the separation ratio of Janus droplets based on We and α, and the influence of droplet size on asymmetric bouncing is discussed. This study also examines the threshold We at which separation begins after impact, varying with droplet size and α. In addition, the shape evolutions of the droplets are discussed for various initial interface angles to understand the bouncing behavior and separation efficiency. This study is expected to provide valuable strategies for controlling droplet behavior and separation in applications such as liquid purification, rheology, and solidification.
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Hasegawa, Koji, Ayumu Watanabe, Akiko Kaneko i Yutaka Abe. "Coalescence Dynamics of Acoustically Levitated Droplets". Micromachines 11, nr 4 (26.03.2020): 343. http://dx.doi.org/10.3390/mi11040343.
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The contactless coalescence of a droplet is of paramount importance for physical and industrial applications. This paper describes a coalescence method to be used mid-air via acoustic levitation using an ultrasonic phased array system. Acoustic levitation using ultrasonic phased arrays provides promising lab-on-a-drop applications, such as transportation, coalescence, mixing, separation, evaporation, and extraction in a continuous operation. The mechanism of droplet coalescence in mid-air may be better understood by experimentally and numerically exploring the droplet dynamics immediately before the coalescence. In this study, water droplets were experimentally levitated, transported, and coalesced by controlled acoustic fields. We observed that the edges of droplets deformed and attracted each other immediately before the coalescence. Through image processing, the radii of curvature of the droplets were quantified and the pressure difference between the inside and outside a droplet was simulated to obtain the pressure and velocity information on the droplet’s surface. The results revealed that the sound pressure acting on the droplet clearly decreased before the impact of the droplets. This pressure on the droplets was quantitatively analyzed from the experimental data. Our experimental and numerical results provide deeper physical insights into contactless droplet manipulation for futuristic lab-on-a-drop applications.
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Zhang, Yixin, Ruolin Dong, Honghui Shi i Jinhong Liu. "Experimental Investigations on the Deformation and Breakup of Hundred-Micron Droplet Driven by Shock Wave". Applied Sciences 13, nr 9 (29.04.2023): 5555. http://dx.doi.org/10.3390/app13095555.
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This study examines the process of a 240 µm droplet breakup under a shock wave through experiments using a double-pulse laser holographic test technique on a shock tube. The technique allowed for high-resolution data to be obtained at the micron-nanosecond level, including the Weber number distribution of deformation and breakup modes for droplets of different sizes and loads. Results were compared with larger droplets at the same Weber number, revealing that higher Weber numbers result in more difficulty in droplet breakup, longer deformation times, and increased deformation behavior. At low Weber numbers within the critical range, changes in droplet diameter affect the Rayleigh–Taylor waves and alter the droplet’s characteristics. The study also investigates the laws and reasons behind windward displacement variation for hundred-micron droplets at different Weber numbers over time.
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Theodorou, Nicolas T., Alexandros G. Sourais i Athanasios G. Papathanasiou. "Simulation of Electrowetting-Induced Droplet Detachment: A Study of Droplet Oscillations on Solid Surfaces". Materials 16, nr 23 (23.11.2023): 7284. http://dx.doi.org/10.3390/ma16237284.
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The electrowetting-induced detachment of droplets from solid surfaces is important for numerous applications in the fields of heat transfer and fluid mechanics. The forced oscillations of droplets on solid surfaces and their ability to detach are studied. In this study, the process is efficiently simulated by implementing a powerful methodology developed by our team. Our results agree with experiments showing that optimal detachment, in terms of actuation energy, is achieved when the application of voltage is synchronized with the spreading time of the droplet. Under these conditions, the droplet oscillates with a period close to that of a mirrored Rayleigh droplet. The relationship between the droplet’s oscillation period and its physical properties is examined. During voltage-droplet synchronization, the droplet’s ability to detach depends mostly on its contact angle, its viscosity, and the applied voltage. An energy analysis is also conducted, revealing how energy is supplied to the droplet by electrowetting-induced detachment.
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Dembia, Christopher Lee, Yu Cheng Liu i C. Thomas Avedisian. "AUTOMATED DATA ANALYSIS FOR CONSECUTIVE IMAGES FROM DROPLET COMBUSTION EXPERIMENTS". Image Analysis & Stereology 31, nr 3 (5.09.2012): 137. http://dx.doi.org/10.5566/ias.v31.p137-148.
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A simple automated image analysis algorithm has been developed that processes consecutive images from high speed, high resolution digital images of burning fuel droplets. The droplets burn under conditions that promote spherical symmetry. The algorithm performs the tasks of edge detection of the droplet’s boundary using a grayscale intensity threshold, and shape fitting either a circle or ellipse to the droplet’s boundary. The results are compared to manual measurements of droplet diameters done with commercial software. Results show that it is possible to automate data analysis for consecutive droplet burning images even in the presence of a significant amount of noise from soot formation. An adaptive grayscale intensity threshold provides the ability to extract droplet diameters for the wide range of noise encountered. In instances where soot blocks portions of the droplet, the algorithm manages to provide accurate measurements if a circle fit is used instead of an ellipse fit, as an ellipse can be too accommodating to the disturbance.
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Lyu, Sijia, Varghese Mathai, Yujie Wang, Benjamin Sobac, Pierre Colinet, Detlef Lohse i Chao Sun. "Final fate of a Leidenfrost droplet: Explosion or takeoff". Science Advances 5, nr 5 (maj 2019): eaav8081. http://dx.doi.org/10.1126/sciadv.aav8081.
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When a liquid droplet is placed on a very hot solid, it levitates on its own vapor layer, a phenomenon called the Leidenfrost effect. Although the mechanisms governing the droplet’s levitation have been explored, not much is known about the fate of the Leidenfrost droplet. Here we report on the final stages of evaporation of Leidenfrost droplets. While initially small droplets tend to take off, unexpectedly, the initially large ones explode with a crack sound. We interpret these in the context of unavoidable droplet contaminants, which accumulate at the droplet-air interface, resulting in reduced evaporation rate, and contact with the substrate. We validate this hypothesis by introducing controlled amounts of microparticles and reveal a universal 1/3-scaling law for the dimensionless explosion radius versus contaminant fraction. Our findings open up new opportunities for controlling the duration and rate of Leidenfrost heat transfer and propulsion by tuning the droplet’s size and contamination.
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Yoon, Dong, Daiki Tanaka, Tetsushi Sekiguchi i Shuichi Shoji. "Size-Dependent and Property-Independent Passive Microdroplet Sorting by Droplet Transfer on Dot Rails". Micromachines 9, nr 10 (11.10.2018): 513. http://dx.doi.org/10.3390/mi9100513.
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A fully passive microdroplet sorting method is presented in this paper. On the rails with dot patterns, the droplets were sorted in different ways depending on their size. However, the effect of droplet properties on the threshold size of the sorting was eliminated. The droplet positions on two railways and the Laplace pressure of the droplets on the dot patterns allowed selective droplet transfer according to size. Different gaps between the rails altered the threshold size of the transfer. However, the threshold size was independent of the droplet’s surface tension and viscosity because the droplet transfer utilized only the droplet position and Laplace pressure without lateral flow to sort targets. This feature has a high potential for bio/chemical applications requiring categorization of droplet targets consisting of various mixtures as pre- or post-elements.
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Hein, Michael, Michael Moskopp i Ralf Seemann. "Flow field induced particle accumulation inside droplets in rectangular channels". Lab on a Chip 15, nr 13 (2015): 2879–86. http://dx.doi.org/10.1039/c5lc00420a.
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We present accumulation of sedimenting particles/cells within elongated droplets. Particle patterns evolve with droplet velocity, as explained by a topological change of the internal flow and the droplet's outer shape.
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Ochowiak, Marek, Zdzisław Bielecki, Michał Bielecki, Sylwia Włodarczak, Andżelika Krupińska, Magdalena Matuszak, Dariusz Choiński, Robert Lewtak i Ivan Pavlenko. "The D2-Law of Droplet Evaporation When Calculating the Droplet Evaporation Process of Liquid Containing Solid State Catalyst Particles". Energies 15, nr 20 (16.10.2022): 7642. http://dx.doi.org/10.3390/en15207642.
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The review presents the D2-law of droplet evaporation, which is used to describe the spraying process involving the evaporation of droplets. This law, the subject of numerous publications, can be successfully applied to describe the droplet evaporation process under various conditions, including the calculations of the process of feeding the boiler with a liquid that contains catalyst particles. To date, not a lot of work has been devoted to this issue. The paper is a continuation of previous research concerning the spraying of liquids with a catalyst, which improves the efficiency of the process. The conducted analysis showed that the experimental data from previously published work are very compatible with the data obtained from the D2-law of droplet evaporation. At the standard speed of about 20 m/s of an aerosol flowing through a dust duct, droplets in the stream should be observed up to a distance of 1 m from the outlet of the apparatus supplying the system. Under such flow conditions, a droplet’s lifetime must be above 0.05 s. The dependence between a droplet’s lifetime and its diameter and temperature was determined. The obtained results confirmed that the effective droplet diameter is above 30 µm. Such droplets must be generated and then fed to the boiler for the catalyst to work properly. This law is an engineering approach to the problem, which uses relatively simple model equations in order to determine the evaporation time of a droplet.
Rozprawy doktorskie na temat "Droplets"
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Umapathi, Udayan. "Droplet IO : programmable droplets for human-material interaction". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/114062.
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Thesis: S.M., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 87-93).
In this thesis, I propose aqueous droplets as a form of programmable material that can computationally transform its physical properties. Liquid matter can undergo physical transformation through interfacial forces and surface tension. I introduce a system called DropletIO to regulate interfacial forces through a programmable electric field. The system can actuate and sense macro-scale (micro-liter to milli-liter) droplets on arbitrary planar and curved surfaces. The system can precisely move, merge, split, and change shape of droplets and thus enables a range of applications with human interactivity, information displays, parallelized programmable chemistry and dynamically tunable optics. DropletIO system uses electrowetting on dielectric (EWOD) to manipulate droplets. EWOD is a physical phenomenon where a polar droplet on a dielectric surface is attracted to a charged electrode. I constructed EWOD arrays with integrated actuation and sensing on inexpensive printed circuit boards that can scale to arbitrarily large areas and different form factors. Additionally, in this thesis I discuss how semiconductor device scaling applies to electrowetting for smaller volume droplets and hence miniaturized programmable lab-on-a-chip. Droplet based microfluidics is extensively used in biology and chemistry. In this thesis I describe two novel fluid manipulation mechanism for microfluidics. First, I show an approach for splitting aqueous droplets on an open digital microfluidic platform and thus a system capable of performing a complete set of microfluidic operations on an open surface. Second, I demonstrate how electrowetting platforms can handle large volume fluids, and hence enable a new direction in programmable fluid handling called digital millifluidics.
by Udayan Umapathi.
S.M.
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Sahu, Sucharita. "Thermal state of Sn-Pb droplets in the droplet-based manufacturing process". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/34081.
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Hager, Darcy B. "Investigations into exploding droplets". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq22991.pdf.
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Wilms, Jochen. "Evaporation of multicomponent droplets". München Verl. Dr. Hut, 2005. http://deposit.d-nb.de/cgi-bin/dokserv?idn=979033012.
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Dunn, Gavin J. "Non-isothermal liquid droplets". Thesis, University of Strathclyde, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501697.
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Two problems concerning sessile liquid droplets are considered. First we report the results of physical experiments that demonstrate the strong influence of the thermal conductivity of the substrate and the nature of the atmosphere on the diffusion-dominated evaporation of a pinned sessile liquid droplet without external heating or cooling. We capture this behaviour in a mathematical model including the variation of the saturation concentration with temperature, and hence coupling the problems for the vapour concentration in the atmosphere and the temperature in the liquid and the substrate. Furthermore, we show that including two ad hoc improvements to the model gives excellent quantitative agreement with experiments. We also extend the model to include the effect of reduced atmospheric pressure and different gases, for which we again find good agreement with experiments. We then consider the special case in which both the droplet and the substrate are thin, in the extreme situation in which the substrate has a high thermal resistance relative to the droplet.
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Khare, Prashant. "Breakup of liquid droplets". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/53395.
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Liquid droplet breakup and dynamics is a phenomena of immense practical importance in a wide variety of applications in science and engineering. Albeit, researchers have been studying this problem for over six decades, the fundamental physics governing droplet deformation and fragmentation is still unknown, not to mention the formulation and development of generalized correlations to predict droplet dynamics. The presence of disparate length and time scales, along with the complex unsteady physics, makes this a formidable problem, theoretically, experimentally and computationally. One of the important applications of interest and the motivation for the current research is a liquid fueled propulsion device, such as diesel, gas turbine or rocket engine. Droplet vaporization and ensuing combustion is accelerated if the droplet size is smaller, which makes any process leading to a reduction in drop size of prime importance in the combustion system design. This thesis is an attempt to address several unanswered questions currently confronting the spray community. Unanswered questions include identification and prediction of breakup modes at varying operating conditions, quantitative description of fundamental processes underlying droplet breakup and generalized correlations for child droplet size distributions and drag coefficient associated with the deformation and fragmentation of Newtonian and non-Newtonian fluids.
The present work is aimed at answering the above questions by investigating the detailed flowfield and structure dynamics of liquid droplet breakup process and extracting essential physics governing this complex multiphase phenomena. High-fidelity direct numerical simulations are conducted using a volume-of-fluid (VOF) interface capturing methodology. To isolate the hydrodynamic mechanisms dictating droplet breakup phenomena, evaporation and compressibility are neglected, and numerical studies are performed for incompressible fluids at isothermal conditions.
For Newtonian fluids, four different mechanisms are identified- oscillatory, bag, multimode and shear breakup modes. Various events during the deformation and fragmentation process are quantitatively identified and correlations are developed to predict the breakup mechanisms and droplet size distributions for a broad range of operating conditions. It was found that for We > 300 and Oh < 0.1 for rho_l/rho_g = 8.29, the child droplet size distributions can be modeled by a log-normal distribution. A correlation to predict the sauter mean diameter, d32, is also developed, given by d32 / D = 8We^-0.72 / Cd.
Temporal evolution of momentum balance and droplet structure are also used to calculate the drag coefficient at each time step from first principles. Results show that the drag coefficient first increases to a maximum as the droplet frontal area increases and then decreases at the initiation of breakup. The drag coefficient reaches a steady value at the end of droplet lifetime, corresponding to the momentum retained by the droplet. A correlation to predict the time-mean drag coefficient given by, Cd / Cd,0 = 2We-^0.175, is developed, which indicates that the time averaged drag coefficient decreases with Weber number.
The motivation to study non-Newtonian liquid droplet breakup stems from the various advantages gelled propellants offer as compared to traditional liquid or solid propellants in combustion systems, particularly in rocket engines. It was found that the breakup behavior of pseudoplastic, non-Newtonian liquids is drastically different as compared to Newtonian droplets. Several flow features commonly exhibited by non-Newtonian fluids are observed during the breakup process. The breakup initiates with the formation of beads-in-a-string due to the non-Newtonian nature of the fluid under consideration. This is followed by rapid rotation of the droplet with the appearance of helical instability and liquid budges, which forms the sites for primary and satellite droplet shedding. Child droplet size distribution are also examined and it is found that a Gaussian curve universally characterizes the droplets produced during non-Newtonian droplet breakup process.
To put all things in perspective, the objectives of the thesis were two folds: (1) elucidate breakup physics for Newtonian and non-Newtonian liquid droplet deformation and breakup, and (2) develop correlations which can be used in an Eulerian-Lagrangian framework to study large-scale engineering problems. It is hoped that this research contributed to droplet breakup and dynamics literature by providing a more thorough and quantitative understanding of the breakup phenomena of liquid droplets and furnished models which can be used in future research endeavors.
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Cherng, Jean-Pei Jeanie. "Solidification and cooling analysis of aluminum alloy droplets with the uniform droplet spray process". Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/36325.
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Marangoni, Federico. "Filter cleaning with liquid droplets". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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L’obiettivo del lavoro svolto è quello di identificare una modalità economica ed applicabile per la pulizia e rigenerazione di filtri di profondità, in particolare nella filtrazione di solidi da correnti gassose. Si ha attualmente mancanza di un tale metodo, che consentirebbe di poter rigenerare il filtro senza che debba essere necessariamente sostituito.
Il lavoro consiste in un approccio sperimentale che studia una singola fibra impolverata da particelle solide. Sono stati proposti dei modelli che descrivono le interazioni tra particella, fibra e liquido. Da questo è stato ricavato un criterio teorico per determinare la riuscita o meno della rimozione di una singola particella solida adesa ad una fibra posta verticalmente e sottoposta al passaggio di un film di liquido con un determinato spessore.
L’apparato sperimentale predisposto permette il fissaggio della fibra, sulla quale vengono fatte scorrere le gocce del liquido di pulizia. Tali gocce sono osservate nella discesa con una fotocamera ad alta frequenza. L'appartato sperimentale ha permesso di variare i principali parametri sperimentali e di testare diverse combinazioni fibra-particelle.
Il parametro chiave nella pulizia è stato individuato nella forza di adesione, dipendente dal liquido utilizzato per la pulizia. Dal punto di vista geometrico, la geometria più affine alla pulizia si è rivelata la geometria cilindrica di piccolo diametro a sfavore di una geometria planare.
L’utilizzo di gocce di liquido più grandi e l’uso di un numero elevato di gocce permette di migliorare il livello di pulizia: entrambi i fattori possono restituire un vantaggio nella pulizia ma si contrappongono al costo materiale del liquido.
Nel complesso, la metodologia di pulizia proposta si è rivelata promettente, con ampie possibilità di essere estesa a filtri industriali.
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Jalaal, Maziyar. "Controlled spreading of complex droplets". Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/60120.
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The current thesis investigates the controlled spreading of droplets of complex fluids. This thesis makes four primary scientific contributions. Firstly, we provide detailed theoretical analysis on spreading of yield stress fluids. We employ lubrication theory, asymptotic solutions, and numerical simulations to explain the dynamics and final static shape of a viscoplastic droplet on a solid horizontal surface. We show that the final radius of the droplet becomes smaller with increasing the yield stress. Secondly, we provide experimental data to verify our theoretical solutions. In our experiments, we first provide a method to eliminate the apparent slip of the yield stress fluid. The method uses a chemical modification of glass surfaces to generate permanent positive charges, resulting in a no-slip boundary condition. We directly observe the slip and no-slip of the Carbopol droplets, using a visualization method based on confocal microscopy. We then perform shadowgraphy experiments to measure the final radius of the droplets under different conditions such as extruding and impacting droplets.
We compare the theoretical and experimental results and discuss the similarities and differences. Briefly, the asymptotic solutions overestimates the experimental results (most likely due to the assumption of a shallow layer), while numerical solutions are much closer to the experimental outcomes. Thirdly, we provide a comprehensive rheological characterization of a particular thermo-responsive fluid, Pluronic F127. We show that the aqueous solution of the polymer undergoes a sol(Newtonian)-gel(yield stress) transition upon heating. We further characterize the properties of the gel in detail. Finally, we show one can thermally trigger a thermo-responsive droplet to externally control the final shape of the droplet on a surface. In short, the final radius of the droplet can be controlled by heating the surface; for a given concentration, the larger the surface temperature, the smaller the final shape of a droplet. In the same part of the thesis, we introduce a novel experimental method based on optical coherence tomography to identify the solidified region inside a droplet.Applied Science, Faculty of
Graduate
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Khatchadourian, Armen. "Lipid droplets under stressful conditions". Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116901.
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Lipid droplets (LDs) are phylogenetically conserved and ubiquitous organelles with many cellular functions. In the last two decades, our understanding of LD biology and of their roles in physiological processes has increased dramatically. In addition, increasing evidence suggests that LDs are highly involved in inflammatory processes, and in metabolic disorders such as type 2 diabetes mellitus (T2DM). Despite such advancement, many aspects of LD biology and of their roles in health and disease remain unknown.The core of LDs is highly enriched with neutral lipids and these can be mobilized to provide metabolic energy. The phospholipid monolayer surrounding the LD core is associated with a wide variety of proteins, including structural and signaling proteins, as well as metabolic enzymes. While LDs may be induced by physiological stimuli such as dietary fatty acids, they can also be formed under stressful conditions, in the absence of such fatty acids. However, exactly how cellular stress leads to LD accumulation remains unclear. Our main objective is to understand the regulation of LD formation under stressful conditions, specifically oxidative stress, inflammation, and metabolic stress. We first investigated LDs in cells exposed to environmental stressors, namely cytotoxic metallic nanoparticles and reactive oxygen species. LD formation and expression of perilipin-2, a key structural LD protein, were highly increased in rodent cells exposed to these stress agents. Interestingly, supplementation with antioxidant N-acetyl cysteine or pharmacological inhibition of p38 mitogen activated protein kinase (MAPK) reduced stress-induced LD accumulation, suggesting that oxidative stress and p38 MAPK activation play a role in the induction of LD formation. Inflammatory leukocytes and macrophages contain a large number of LDs. While this phenomenon has been widely investigated in peripheral immune cells, its explanation remains elusive in immune cells of the central nervous system. We therefore investigated LD dynamics and regulation in microglia, the resident immune cells in the brain. We found that stimulation of microglia with toll-like receptor 4 (TLR4) agonist, lipopolysaccharides (LPS), increased LD formation and perilipin-2 expression in an Akt and p38 MAPK-dependent manner. Interestingly, LPS-induced LDs extensively colocalized with cytosolic phospholipase A2-α (cPLA2-α), a key enzyme involved in the synthesis of eicosanoids, which are inflammatory lipid mediators. Collectively, these findings imply that LD formation may contribute to increased eicosanoid synthesis in activated microglia and could be microglial biomarkers of inflammation in the central nervous system. To gain a better insight into the role of LDs in human pathology, we sought to examine alterations in LD metabolism in pancreatic tissue obtained from T2DM and obese individuals. Immunohistochemical studies revealed increased islet and extra-islet perilipin-2 expression in tissues from lean or obese T2DM donors, but not in non-T2DM obese donors, suggesting that the diabetic status, but not the obesity status, is a requirement for increasing perilipin-2 expression and LD formation. Gene expression analysis by RT-qPCR confirmed the increase in perilipin-2 expression and revealed significant alterations in several genes related to islet function, metabolism and antioxidant defense. These alterations seem to be consistently associated with obesity and T2DM and imply an adaptive and compensatory response to insulin resistance and metabolic stress. In summary, our studies show that LDs are an integral part of the adaptive cellular response to oxidative, inflammatory and metabolic stress. Perhaps, the most important challenge in LD research in the upcoming decade will be to determine how the subcellular lipid and protein composition of this organelle affects its function in different cells.Les gouttelettes lipidiques (GL) sont des organites phylogénétiquement conservées et impliquées dans plusieurs fonctions cellulaires. Durant les deux dernières décennies, notre compréhension des rôles biologiques et physiologiques des GL a augmenté de manière draconienne. Plusieurs observations suggèrent fortement que les GL jouent un rôle important dans l'inflammation, ainsi que dans les désordres métaboliques tels que le diabète de type 2 (DT2). Malgré cette avancée, plusieurs aspects de la biologie des GL et de leurs rôles dans des maladies demeurent méconnus.Le centre des GL est riche en lipides neutres qui peuvent se mobiliser et servir comme source d'énergie. La couche phospholipidique entourant le centre de la GL est associée à plusieurs protéines et enzymes métaboliques. Bien que les GL puissent être induites par des acides gras, elles peuvent aussi l'être dans des conditions de stress. Par contre, les mécanismes de l'accumulation de GL par des conditions de stress ne sont pas encore bien compris. Notre objectif principal est de comprendre la régulation de la formation de GL par le stress oxydatif, l'inflammation et le stress métabolique. Premièrement, nous avons investigué les GL dans des cellules exposées à des stresseurs tels que des nanocrystaux métalliques et des dérivés réactifs d'oxygène. La formation de GL et l'expression de perilipin-2, qui est une protéine structurelle des GL, ont tous deux augmenté dans les cellules stressées. De plus, une supplémentation en antioxydant (n-acétylcystéine) ou un traitement avec un inhibiteur de p38 MAPK a réduit l'accumulation de GL causée par le stress. Ces observations suggèrent que le stress oxydatif et p38 MAPK jouent un rôle dans l'accumulation de GL dans des cellules stressées. Il est bien connu que les leucocytes et macrophages qui sont engagés dans l'inflammation contiennent une grande quantité de GL. Même si ce phénomène a bien été exploré dans les cellules immunitaires périphériques, il reste inexploré dans le système nerveux central (SNC). Ce faisant, nous avons investigué la dynamique et la régulation des GL dans les microglies, les cellules résidentes immunitaires dans le cerveau. Nous avons trouvé que dans les microglies stimulées avec les lipopolysaccharides (LPS), les GL et l'expression de perilipin-2 ont augmenté d'une manière dépendante de l'activation de l'Akt et p38 MAPK. Dans ces cellules activées, la phospholipase cytosolique A2-α (PLC A2-α), une enzyme fonctionnant dans la synthèse d'éicosanoides, des médiateurs lipidiques inflammatoires, colocalisait avec les GL. Ensemble, ces résultats indiquent que la formation de GL pourrait contribuer à la synthèse d'éicosanoides dans les microglies activées et servir de biomarqueurs d'inflammation dans le SNC.Pour mieux comprendre le rôle des GL dans la pathologie humaine, nous les avons examinées dans des tissues pancréatiques provenant de patients obèses ou diabétiques T2. Nos études immunohistochimiques ont révélé une augmentation de perilipin-2 dans les îlots de Langerhans chez les patients diabétiques obèses ou maigres, mais pas dans ceux de patients non-diabétiques. Ceci suggère que le DT2, mais non l'obésité, est requis pour une augmentation de perilipin-2 dans le pancréas. L'analyse d'expression de gènes par RT-PCR a confirmé l'augmentation de perilipin-2 observé antérieurement dans les îlots et a également révélé des altérations dans des gènes reliés aux fonctions des îlots, au métabolisme, et aux défenses anti-oxydantes. Ces changements, qui sont souvent associés à l'obésité et au DT2, constituent un mécanisme d'adaptation à la résistance à l'insuline et au stress métabolique.Pour résumer, nos études démontrent que l'accumulation de GL fait partie intégrante de l'adaptation des cellules au stress. Durant la prochaine décennie, le plus grand obstacle dans la recherche sur les GL sera de déterminer comment la composition lipidique ou protéinique de ces organites affecte leurs fonctions biologiques.
Książki na temat "Droplets"
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Swiderski, Cassandra. Narrow droplets. Bloomington, IN: iUniverse, 2012.
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Ajileye, Gbenga. Droplets: Poetry. Owerri, Nigeria: Taurus Publications, 2009.
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Basu, Saptarshi, Avinash Kumar Agarwal, Achintya Mukhopadhyay i Chetankumar Patel, red. Droplets and Sprays. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-7449-3.
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Sazhin, Sergei. Droplets and Sprays. London: Springer London, 2014. http://dx.doi.org/10.1007/978-1-4471-6386-2.
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Frohn, Arnold, i Norbert Roth. Dynamics of Droplets. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-662-04040-9.
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Frohn, Arnold. Dynamics of Droplets. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000.
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Sazhin, S. S. Droplets and sprays. London: Springer, 2014.
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Kapljice mora =: Sea droplets. Rijeka: Adamić, 2002.
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Rouault, Mathieu. Spray Droplets under Turbulent Conditions. Roskilde, Denmark: Riso National Laboratory, 1990.
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Posnjak, Gregor. Topological Formations in Chiral Nematic Droplets. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-98261-8.
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Zhang, Jie, Yunteng He, Lei Lei, Yuzhong Yao, Stephen Bradford i Wei Kong. "Electron Diffraction of Molecules and Clusters in Superfluid Helium Droplets". W Topics in Applied Physics, 343–79. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-94896-2_8.
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AbstractIn an effort to solve the crystallization problem in crystallography, we have been engaged in developing a method termed “serial single molecule electron diffraction imaging” (SS-EDI). The unique features of SS-EDI are superfluid helium droplet cooling and field-induced orientation. With two features combined, the process constitutes a molecular goniometer. Unfortunately, the helium atoms surrounding the sample molecule also contribute to a diffraction background. In this chapter, we analyze the properties of a superfluid helium droplet beam and its doping statistics, and demonstrate the feasibility of overcoming the background issue by using the velocity slip phenomenon of a pulsed droplet beam. Electron diffraction profiles and pair correlation functions of monomer-doped droplets, small cluster and nanocluster -doped droplets are presented. The timing of the pulsed electron gun and the effective doping efficiency under different dopant pressures can both be controlled for size selection. This work clears any doubt of the effectiveness of superfluid helium droplets in SS-EDI, thereby advancing the effort in demonstrating the “proof-of-concept” one step further.
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Tanyag, Rico Mayro P., Bruno Langbehn, Thomas Möller i Daniela Rupp. "X-Ray and XUV Imaging of Helium Nanodroplets". W Topics in Applied Physics, 281–341. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-94896-2_7.
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AbstractX-ray and extreme ultraviolet (XUV) coherent diffractive imaging (CDI) have the advantage of producing high resolution images with current spatial resolution of tens of nanometers and temporal resolution of tens of femtoseconds. Modern developments in the production of coherent, ultra-bright, and ultra-short X-ray and XUV pulses have even enabled lensless, single-shot imaging of individual, transient, non-periodic objects. The data collected in this technique are diffraction images, which are intensity distributions of the scattered photons from the object. Superfluid helium droplets are ideal systems to study with CDI, since each droplet is unique on its own. It is also not immediately apparent what shapes the droplets would take or what structures are formed by dopant particles inside the droplet. In this chapter, we review the current state of research on helium droplets using CDI, particularly, the study of droplet shape deformation, the in-situ configurations of dopant nanostructures, and their dynamics after being excited by an intense laser pulse. Since CDI is a rather new technique for helium nanodroplet research, we also give a short introduction on this method and on the different light sources available for X-ray and XUV experiments.
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Schlaghaufer, Florian, Johannes Fischer i Alkwin Slenczka. "Electronic Spectroscopy in Superfluid Helium Droplets". W Topics in Applied Physics, 179–240. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-94896-2_5.
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AbstractElectronic spectroscopy has been instrumental in demonstrating the properties of helium droplets as a cryogenic matrix for molecules. The electronic spectrum of glyoxal, which was one of the first molecules investigated in helium droplets by means of electronic spectroscopy, showed two features that provided convincing evidence that the droplets were superfluid. These were free rotation and the distinct shape of the phonon side band which could be directly assigned to the characteristic dispersion curve of a superfluid. On closer examination, however, details such as increased moments of inertia and a spectral response on the droplet size distribution revealed unexpected features of microsolvation in the superfluid helium. In the course of studying many different molecules, it has become clear that electronic spectroscopy in helium droplets provides insight into the detailed effects of microsolvation. These in turn lead to numerous questions regarding the interaction with the superfluid which are discussed in this chapter. In addition, the influence of microsolvation in helium droplets on van der Waals clusters generated inside helium droplets are discussed. Finally, the effect of helium solvation on unimolecular or bimolecular elementary chemical reactions is evaluated in comparison with corresponding experiments in the gas phase. Particular focus of this article lies on the spectral features related to helium solvation which are not yet fully understood.
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Reutzsch, Jonathan, Verena Kunberger, Martin Reitzle, Stefano Ruberto i Bernhard Weigand. "Investigation of the Behaviour of Supercooled Droplets Concerning Evaporation, Sublimation and Freezing Under Different Boundary Conditions". W Fluid Mechanics and Its Applications, 149–68. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-09008-0_8.
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AbstractPhase change processes of supercooled droplets at different boundary conditions are presented. This study is a summary of the current developments within subproject B1 of the SFB-TRR 75 with the focus on evaporation, sublimation, and freezing of supercooled droplets. To this end, new numerical methods to describe the phase transition were developed and novel strategies dealing with the challenges of droplets under extreme conditions are presented. The numerical solution procedure of all phase changes are summarized in a compact way within this work. In order to validate the numerical models, experiments were conducted. For this, new experimental setups and approaches were developed. These comprise a test chamber for optical levitation of supercooled droplets, which is able to trap a droplet by means of a laser beam at subzero temperatures and variable ambient humidity. Comparisons of the numerical simulations and the conducted experiments are presented for several phase change processes. The results are in very good agreement and proof the capability of the methods.
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Kolev, Nikolay Ivanov. "Liquid droplets". W Multiphase Flow Dynamics 3, 283–317. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-21372-4_12.
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Hansen, Klavs. "He Droplets". W Statistical Physics of Nanoparticles in the Gas Phase, 349–70. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-90062-9_12.
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Heering, Peter, i Troublesome Droplets. "Troublesome Droplets". W Adapting Historical Knowledge Production to the Classroom, 103–11. Rotterdam: SensePublishers, 2011. http://dx.doi.org/10.1007/978-94-6091-349-5_7.
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Scholz, Fritz, Uwe Schröder, Rubin Gulaboski i Antonio Doménech-Carbó. "Immobilized Droplets". W Electrochemistry of Immobilized Particles and Droplets, 225–95. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-10843-8_6.
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Hansen, Klavs. "He Droplets". W Statistical Physics of Nanoparticles in the Gas Phase, 229–45. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-5839-1_10.
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Löwe, Jens-Michael, Michael Kempf i Volker Hinrichsen. "Mechanical and Electrical Phenomena of Droplets Under the Influence of High Electric Fields". W Fluid Mechanics and Its Applications, 355–72. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-09008-0_18.
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AbstractHigh-voltage composite insulators are specially designed to withstand different environmental conditions to ensure a reliable and efficient electric power distribution and transmission. Especially, outdoor insulators are exposed to rain, snow or ice, which might significantly affect the performance of the insulators. The interaction of sessile water droplets and electric fields is investigated under various boundary conditions. Besides the general behavior of sessile droplets, namely the deformation and oscillation, the inception field strength for partial discharges is examined depending on the droplet volume, strength and frequency of the electric field and the electric charge. Particularly, the electric charge is identified to significantly affect the droplet behavior as well as the partial discharge inception field strength. In addition to ambient conditions, the impact of electric fields on ice nucleation is investigated under well-defined conditions with respect to the temperature and electric field strength. High electric field strengths are identified to significantly promote ice nucleation, especially in case of alternating and transient electric fields. Different influencing factors like the strengths, frequencies and time constants of the electric fields are investigated. Consequently, the performed experiments enhance the knowledge of the behavior of water droplets under the impact of electric fields under various conditions.
Streszczenia konferencji na temat "Droplets"
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Traipattanakul, B., C. Y. Tso i Christopher Y. H. Chao. "Study of Electrostatic-Induced Jumping Droplets on Superhydrophobic Surfaces". W ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70311.
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Condensation of water vapor is an important process utilized in energy/thermal/fluid systems. When droplets coalesce on the non-wetting surface, excess surface energy converts to kinetic energy leading to self-propelled jumping of merged droplets. This coalescing-jumping-droplet condensation can better enhance heat transfer compared to classical dropwise condensation and filmwise condensation. However, the resistance force can cause droplets to return to the surface. These returning droplets can either coalesce with neighboring droplets and jump again, or adhere to the surface. As time passes, these adhering droplets can become larger leading to progressive flooding on the surface, limiting heat transfer performance. However, an electric field is known to be one of the effective methods to prevent droplet return and to address the progressive flooding issue. Therefore, in this study, an experiment is set up to investigate the effects of applied electrical voltages between two parallel copper plates on the jumping height with respect to the droplet radius and to determine the average charge of coalescing-jumping-droplets. Moreover, the gravitational force, the drag force, the inertia force and the electrostatic force as a function of the droplet radius are also discussed. The gap width of 7.5 mm and the electrical voltages of 50 V, 100 V and 150 V are experimentally investigated. Droplet motions are captured with a high-speed camera and analyzed in sequential frames. The results of the study show that the applied electrical voltage between the two plates can reduce the resistance force due to the droplet’s inertia and can increase the effects of the electrostatic force. This results in greater jumping heights and the jumping phenomenon of some bigger-sized droplets. With the same droplet radius, the greater the applied electrical voltage, the higher the coalescing droplet can jump. This work can be utilized in several applications such as self-cleaning, thermal diodes, anti-icing and condensation heat transfer enhancement.
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Abushamleh, Mohammed, i Ning Zhang. "CFD Simulation of COVID Aerosol Dispersion in Indoor Environments". W ASME 2021 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/fedsm2021-65877.
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Abstract Computational Fluid Dynamics simulations for the droplet’s dispersion generated by a cough in an indoor background, droplets trajectory, and evaporation time are predicted to be related to the droplet’s diameter and relative humidity. In general, medium-size droplets have higher axial penetration potential, and large droplets tend to settle on the ground due to gravity. Also, larger droplets take a longer time to evaporate. Smaller droplets tend to be suspended in the flow field with small penetration potential and tend to fade faster; smaller droplets < 20 μm evaporate completely before the simulation time reaches 0.75 sec. To study the effect of Relative Humidity (RH) on the evaporation rate, in particular, the present study offers three simulations, all with the same standard room conditions, only differ in relative humidity s 40%, 60%, and 90%. Another source of variability is the cough-expired volume. This study adopts existent experimental work to establish two cough flow rate profiles. The Lagrangian discrete phase model is adopted along with the species model to track and investigate the cough droplet dispersion and evaporation.
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Dehghani-Sanij, Alireza, Greg F. Naterer, Yuri S. Muzychka i Kevin Pope. "Thermal Analysis of Saline Droplet Motion With Cooling in Cold Regions". W ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61097.
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In this paper, a theoretical approach is employed to analyze the thermal behaviour and study the cooling process of water droplets in cold regions. Additionally, the effect of several parameters, such as air temperature, droplet size, initial droplet temperature, relative humidity and droplet salinity on the cooling process is investigated. The model contains convection, evaporation, and radiation heat transfer from the droplet’s surface and a uniform temperature across the droplet. The results illustrate a good agreement between the theoretical predictions and previously measured data. Furthermore, droplet size, air temperature, initial droplet temperature, and droplet flight time have a substantial effect on the droplet cooling process. This model is a useful tool to investigate the thermal behaviour and the cooling process of water droplets.
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Shearer, John, Sue Swinburne i Patrick Dickinson. "Droplets". W British HCI 2015: 2015 British Human Computer Interaction Conference. New York, NY, USA: ACM, 2015. http://dx.doi.org/10.1145/2783446.2783617.
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Bhola, R., i S. Chandra. "Splat Solidification of Tin Droplets". W ITSC 1996, redaktor C. C. Berndt. ASM International, 1996. http://dx.doi.org/10.31399/asm.cp.itsc1996p0657.
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Abstract An experimental study was done of the impact and solidification of tin droplets falling on a stainless steel surface. The surface temperature was varied from 25°C to 240°C. Measurements were made of droplet diameters and contact angles during droplet spread. At a surface temperature of 240°C there was no solidification, and a simple model of liquid droplet impact successfully predicted the extent of droplet spread. Droplets impacting on surfaces at 25°C and 150°C solidified before spreading was complete.
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Burkhart, Collin T., Kara L. Maki i Michael J. Schertzer. "Impact of Particle Selection on Nanoparticle Self-Assembly in Evaporating Colloidal Droplets". W ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-66851.
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Colloidal droplets often leave behind ring-shaped depositions of material after they evaporate called “coffee ring” patterns that are undesirable in many medical diagnostic and printing applications. By applying electric fields to a droplet, additional electrowetting and electrophoretic forces can be applied on the droplet’s contact line and particles, respectively, to suppress this phenomenon. Better understanding of the effects of electrowetting and electrophoresis may lead to novel techniques for nanoparticle self-assembly in evaporating colloidal droplets that are subjected to electric fields. This work experimentally examines the effect of particle selection on nanoparticle deposition in evaporating droplets. Droplets consist of deionized water seeded with polystyrene or titanium oxide nanoparticles on the order of 20 nm. Colloidal droplets are evaporated on substrates coated with an SU-8 photoresist. Before fundamentally understanding the effects of an applied electric field, the evaporative dynamics and resultant colloidal transport in similar unactuated systems must first be understood. Current trials involve studying these unactuated control cases, but future trials will involve droplets actuated on the same material with applied AC or DC electric fields. Droplet interface shapes during evaporation are recorded and compared between trials. Final deposition patterns and their particle distributions are also qualitatively examined. Polystyrene droplets pinned for approximately the first 30% of the total evaporation time and then receded at a constant contact angle and produced ring depositions. Titanium oxide droplets pinned for approximately the first 60% of the total evaporation time and then receded in a slip-stick pattern. These produced more uniform depositions with a less-distinct outer ring, despite pinning for more of the evaporation time. The variations in transient behavior suggest that differences in particle characteristics may be impacting the contact line dynamics and resulting in different final deposition pattern.
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Schoo, Reilly, Alison Hoxie i Joel Braden. "Combustion Characteristics of Butanol-Soybean Oil Blended Droplets". W ASME 2014 8th International Conference on Energy Sustainability collocated with the ASME 2014 12th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/es2014-6320.
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The combustion characteristics of single fuel droplets of soybean oil (SBO) and butanol binary blends simply mixed by volume were experimentally examined. The droplets were supported at an intersection of microfibers in a 100°C combustion chamber at atmospheric pressure in normal gravity. Ignition was achieved via a hot wire igniter. Ignition characteristics and burning behaviors including burning to completion, burning with microexplosion and incomplete combustion were analyzed for initial concentrations ranging from 25–75% butanol. Droplet size and temperature measurements were analyzed throughout the droplet lifetimes. Relative concentrations prior and during combustion were estimated. Temperature measurements at ignition and above the burning droplet were analyzed. The addition of butanol significantly lowered the droplet ignition temperature. All mixtures studied ignited similarly to pure butanol droplets. The results showed consistency with closed-cup flashpoint temperatures of butanol-soybean oil blends. A three-staged burn including a microexplosion was observed for all mixed droplets, which burned completely. The disruptive burning proved to be a result of a diffusion limited gasification mechanism that has been previously linked to bi-component droplets with high volatility differentials. Microexplosions occur as a result of homogeneous nucleation due to superheating of the more volatile component trapped within the droplet at flame shrinkage. Results show that more butanol is burned in the first stage for Bu75 droplets resulting in microexplosions occurring late in the combustion process. For droplets of near equal initial concentrations, the microexplosions occur earlier resulting in less fuel burned in the first stage of combustion and therefore higher concentrations of butanol trapped within the droplet at flame shrinkage. Consequently these mixtures experience more microexplosions and at a greater intensity. The reduced tendency for Bu75 droplets to experience microexplosions suggest that the maximum droplet surface temperature may be depressed compared to droplets of near equal concentrations reducing the possibility for superheating of the droplet interior. Blends of near equal concentrations by volume proved to exhibit the most favorable combustion characteristics. Bu40 exhibited the most violent microexplosions of all mixtures studied.
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Rehman, Hafiz Laiq-ur, Abdelouahab Mohammed-Taifour, Julien Weiss i Patrice Seers. "PLIF Experiments on Evaporating Isolated Droplet and Droplets Array". W 46th AIAA Thermophysics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2016. http://dx.doi.org/10.2514/6.2016-4311.
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Strohm, Eric M., Min Rui, Michael C. Kolios, Ivan Gorelikov i Naomi Matsuura. "Optical droplet vaporization (ODV): Photoacoustic characterization of perfluorocarbon droplets". W 2010 IEEE Ultrasonics Symposium (IUS). IEEE, 2010. http://dx.doi.org/10.1109/ultsym.2010.5935474.
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Kobayashi, Isao, i Mitsutoshi Nakajima. "Micro/Nanochannel Emulsification for Generating Monosize Droplets". W ASME 2012 Third International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/mnhmt2012-75238.
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Emulsification is an important process in various fields including foods, pharmaceuticals, cosmetics, and chemicals. Emulsification operation is commonly conducted using conventional emulsification devices, such as high-speed blenders, colloid mills, high-pressure homogenizers, and ultrasonic homogenizers. However, these emulsification devices result in the production of polydisperse emulsions with wide droplet size distributions and poor controllability in droplet size and its distribution. In contrast, monodisperse emulsions consisting of monosize droplets have received a great deal of attentions over the past decade due to their high-tech applications, e.g., monosize microparticles as spacers for electronic devices and monosize micro-carriers for drug delivery systems (DDS). Our group proposed microchannel (MC) emulsification as a promising technique to produce monodisperse emulsions in the mid 1990s. Micro/Nanochannel (MNC) emulsification enables generating monosize droplets with the smallest coefficient of variation (CV) of below 5% using MC and nanochannel (NC) arrays of unique geometry. The resultant droplet size, which ranged from 0.5 to 200 μm, can be precisely controlled by channel geometry. Droplet generation for MNC emulsification is very mild and does not require any external shear stress; a dispersed phase that passed through channels is transformed spontaneously into monosize droplets inside a continuous-phase domain. The aim of this paper is to present recent developments in MNC emulsification chips, particularly focusing on asymmetric straight-through MC arrays for large-scale production of monodisperse emulsions. Asymmetric straight-through MC array chips were fabricated using a silicon-on-insulator wafer. Numerous asymmetric straight-through MCs each consisting of a microslot and a narrow MC were positioned in the central region of the chip. Monosize droplets were stably generated via asymmetric straight-through MCs at high production rates. Below a critical droplet production rate, monosize droplets were generated via asymmetric straight-through MCs, with droplet size and size distribution independent of the droplet productivity. The use of a large asymmetric straight-through MC array chip achieved the mass production of monosize tetradecane oil droplets at ∼1 L/h. The simulation results using CFD (computational fluid dynamics) agreed well with the experimental results and provided useful information, such as the movement of the oil-water interface during droplet generation. Monosize submicron droplets were also obtained using NC emulsification chips made of single-crystal silicon.
Raporty organizacyjne na temat "Droplets"
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Asenath-Smith, Emily, Emily Jeng, Emma Ambrogi, Garrett Hoch i Jason Olivier. Investigations into the ice crystallization and freezing properties of the antifreeze protein ApAFP752. Engineer Research and Development Center (U.S.), wrzesień 2022. http://dx.doi.org/10.21079/11681/45620.
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Antifreeze proteins (AFPs) allow biological organisms, including insects, fish, and plants, to survive in freezing temperatures. While in solution, AFPs impart cryoprotection by creating a thermal hysteresis (TH), imparting ice recrystallization inhibition (IRI), and providing dynamic ice shaping (DIS). To leverage these ice-modulating effects of AFPs in other scenarios, a range of icing assays were performed with AFPs to investigate how AFPs interact with ice formation when tethered to a surface. In this work, we studied ApAFP752, an AFP from the beetle Anatolica polita, and first investigated whether removing the fusion protein attached during protein expression would result in a difference in freezing behavior. We performed optical microscopy to examine ice-crystal shape, micro-structure, and the recrystallization behavior of frozen droplets of AFP solutions. We developed a surface chemistry approach to tether these proteins to glass surfaces and conducted droplet-freezing experiments to probe the interactions of these proteins with ice formed on those surfaces. In solution, ApAFP752 did not show any DIS or TH, but it did show IRI capabilities. In surface studies, the freezing of AFP droplets on clean glass surfaces showed no dependence on concentration, and the results from freezing water droplets on AFP-decorated surfaces were inconclusive.
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Videen, Gorden, Wenbo Sun, Qiang Fu, David Secker i Paul Kaye. Light Scattering from Deformed Droplets and Droplets with Inclusions: Volume 2 - Theoretical Results. Fort Belvoir, VA: Defense Technical Information Center, wrzesień 2000. http://dx.doi.org/10.21236/ada383664.
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Secker, David R., Richard Greenaway, Paul H. Kaye, Edwin Hirst i David Bartley. Light Scattering from Deformed Droplets and Droplets with Inclusions: Volume 1 - Experimental Results. Fort Belvoir, VA: Defense Technical Information Center, wrzesień 2000. http://dx.doi.org/10.21236/ada383990.
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Wagner, Matthew, i Marianne M. Francois. Computational Fluid Dynamics of rising droplets. Office of Scientific and Technical Information (OSTI), wrzesień 2012. http://dx.doi.org/10.2172/1050489.
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Luey, K. T., i D. J. Coleman. Formation of Contaminant Droplets on Surfaces. Fort Belvoir, VA: Defense Technical Information Center, grudzień 2006. http://dx.doi.org/10.21236/ada464143.
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Perepezko, J. H. Solidification of Highly Undercooled Liquid Droplets. Fort Belvoir, VA: Defense Technical Information Center, styczeń 1990. http://dx.doi.org/10.21236/ada218776.
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Reyes, C. Dancing Droplets on a Defect Line. Office of Scientific and Technical Information (OSTI), październik 2021. http://dx.doi.org/10.2172/1826866.
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Armijo, Kenneth Miguel, Blake Lance i Clifford K. Ho. Impinging Water Droplets on Inclined Glass Surfaces. Office of Scientific and Technical Information (OSTI), wrzesień 2017. http://dx.doi.org/10.2172/1395759.
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Kreidenweis, S. M. Modeling of aqueous chemistry in cloud droplets. Office of Scientific and Technical Information (OSTI), luty 1992. http://dx.doi.org/10.2172/10165473.
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Talley, Douglas G., R. K. Cohn, E. B. Coy, B. Chehroudi i D. W. Davis. Mixing Dynamics of Supercritical Droplets and Jets. Fort Belvoir, VA: Defense Technical Information Center, kwiecień 2005. http://dx.doi.org/10.21236/ada432567.
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