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[Display omitted] The rich variety of patterns induced by evaporating drops containing particles has significant guidance for coating processes, inkjet printing, and nanosemiconductors. However, most existing works construct a uniform pattern by suppressing the coffee ring effect, and establishing the connection between them is still an academic challenge. We report uniform, polygonal, and coffee ring patterns obtained by adjusting the solute concentration that sets in when an ethanol drop with dissolved ibuprofen is deposited on a silicon wafer. Pattern formation involves rich hydrodynamic events: spreading, evaporative instability, dewetting, film formation, and particle deposition. Based on the distinct multiscale properties, this series of patterns is directly connected from the perspective of fractal geometry, which allows us to name them "fractal deposition patterns". A theoretical model considering film stability is established to explain the mechanism behind pattern formation, which is well verified by experiments. This work has presented a unique strategy that can directly connect uniform, polygonal, and coffee ring patterns under the same physics, hoping to provide instructive guidance for practical applications. [ABSTRACT FROM AUTHOR]

The equations governing the motion of a three-dimensional liquid drop moving freely in an unbounded liquid reservoir under the influence of a gravitational force are investigated. Provided the (constant) densities in the two liquids are sufficiently close, existence of a steady-state solution is shown. The proof is based on a suitable linearization of the equations. A setting of function spaces is introduced in which the corresponding linear operator acts as a homeomorphism. [ABSTRACT FROM AUTHOR]

The main purpose of dispersing devices is to convert a continuous flow of liquid into a dispersed system consisting of drops of liquid. There are two ways to convert fluid jets into thin films: hydrostatic (on an inclined plate) and centrifugal (on the film-forming—blade). The process of spraying or dispersing is generally as follows. From the film-forming element (plate or blade), the liquid in the form of a thin flat film moves at a certain relative speed into the gaseous medium, interacting with which the film is destroyed, turns into a stream of drops (spray torch). Many groups of scientists and a number of institutes have been engaged in the study of the spray heat and mass transfer. It makes sense to consider the size of the drops rationally seek to achieve in industrial technology, when using the heat and mass transfer contact devices of the spray type. In other words, what size of droplets should give technical, energy and other advantages for the best use of the effect of the rate of change of the contact surface of the phases? The main disadvantages of fine spraying are: problems of obtaining the minimum sizes (due to big turns of centrifugal sprayers or big pressure and low productivity of nozzle sprayers); high energy consumption; large loss of drops (fighting it is the task, which is even more difficult than getting small drops); large evaporation (i.e., the smaller the diameter of the droplets, the faster they evaporate). The latter can be a useful effect, but sometimes, it is completely unacceptable for many technological processes. Advantages of bulk spraying are quite simple equipment for such spraying, small loss of drops, energy consumption many times less than with traditional methods of spraying liquids (nozzle, centrifugal, etc.). [ABSTRACT FROM AUTHOR]

We analyze different flow regimes of a filament formed by extrusion of a material through a cylindrical die. We deduce that the elongational yield stress of a simple yield stress fluid (i.e., with negligible thixotropy effects) can be determined from the mass of the droplet after filament breakage and an estimation of the critical radius at pinch-off at the solid-liquid regime transition. We demonstrate that such a simple characterization is relevant in a relatively wide range of extrusion velocities, i.e., this velocity slightly affects the drop mass in this range. For the simple yield stress fluids used, Carbopol gel, clay-water paste at different concentrations, and emulsion, covering a large range of yield stress values (50–1000 Pa), the elongational yield stress appears to be equal to the simple shear yield stress times a factor equal to about 1.5 3. As a consequence, this simple test may be used to obtain, almost instantaneously and without sophisticated apparatus (a syringe and a balance are sufficient), a good estimate of the shear yield stress of simple yield stress fluids. In that case, the main source of uncertainty (up to about 20%) is the value of the critical radius at the solid-liquid transition. Finally, we review the operating conditions (material properties and extrusion characteristics) for which we can expect this approach to be valid. [ABSTRACT FROM AUTHOR]

The relevance. The most common fire extinguishing composition for the localization and elimination of natural and man-made fires is water. Almost annual increase in the areas of fires in the boreal zone, as well as the remoteness of fires from water sources, necessitates an increase in the resource efficiency of extinguishing. The main task in extinguishing man-made fires is to reduce the consumption of fire extinguishing agents, which will reduce the risk of excessive water flooding of the premises and material costs for the restoration of facilities. For these purposes, it is advisable to improve existing and develop new fire extinguishing compositions. The insufficient knowledge of the processes occurring during the interaction of drops of various typical fire extinguishing liquids with the surface of combustible materials, and the high scientific and practical significance of such studies determines the relevance. Purpose: to establish the patterns of wetting, spreading and evaporation of drops of fire extinguishing compositions on the surfaces of combustible materials during conductive heating. Object: fire extinguishing compositions (water; flame retardant solutions, FR-Les, bischofite; bentonite suspensions; foam concentrate emulsions) of various concentrations. Methods. The study of wetting and evaporation of drops of fire extinguishing compositions was carried out by the method of a «fixed» drop (placed on a solid surface using an electronic dispenser). To determine the geometric characteristics of the drops, a shadow optical system was used, and the obtained images were processed using special software using the «tangential 1» and «Young–Laplace» methods. Results. The main patterns of wetting and evaporation of drops of fire extinguishing compositions on the surfaces of combustible materials (birch leaves, wood, laminated chipboard, linoleum and polyvinyl chloride) have been established. It is shown that in suppressing the pyrolysis of combustible materials in the depth of the layer, compositions with a lower surface tension, penetrating into deeper layers of combustible material, will be more effective. Under such conditions, fragments of materials heated to high temperatures are cooled, and generation of fuel – gaseous products of thermal decomposition – is suppressed. It was established that the dominant mechanism for suppressing combustion and pyrolysis when extinguishing combustible materials (namely, when using fire retardants, bischofite, bentonite, FR-Les) is the formation of a protective layer on the surface of elements of substances and materials, and not heat absorption during solvent evaporation. The dependences of the time-average evaporation rates of droplets of fire-extinguishing compositions on the surface heating temperature are approximated by the exponential curve WE = a∙Tb.

Contact angle hysteresis (CAH) is a significant factor affecting the drop motion on solid substrates. A model of CAH is introduced to explore the influence of CAH on the dynamics of a sessile drop on a uniformly heated surface, and a two-dimensional evolution equation of the drop thickness is established using the lubrication approximation and Navier slip boundary conditions. A numerical simulation is performed to examine the dynamic behaviors of an evaporating drop, and the drop profile, contact angle, contact line, and moving speed are investigated. Simulated results indicate that the drop evolution process involves drop spreading, pinning, and depinning of the contact line. In the drop spreading stage, when the hysteresis angle increases, the spreading period is shortened, and the spreading radius and spreading speed are reduced; in contrast, the pinning period is raised, and the mass of the drop is apparently reduced with increasing hysteresis angle. In the depinning stage, the CAH declines the contact angle, and a flatter pattern is evolved, thereby improving the heat transfer performance, promoting drop evaporation, and shortening the depinning time. The presence of CAH can speed up the drying of the drop, and the large hysteresis angle leads to faster evaporation. Regulating the CAH is an effective way to manipulate the motion of the contact line for an evaporating drop.

• The wetting of porous surfaces differs from that of dense surfaces due to the liquid's infiltration. • During evaporation, the base of the droplet undergoes three stages: expansion, constant base, and shrinkage. • A theoretical model for the temporal evolution of the contact angle was developed for the second and third stages. This study aims to examine the membrane wetting of a porous cylindrical surface in comparison with dense cylindrical surfaces. Droplets of distilled water, ethyl alcohol, and 35 g/L NaCl solution with an average volume of 5 µl were deposited on a hydrophobic polypropylene (PP) cylindrical membrane with micropores, a dense polypropylene (PP) cylindrical membrane, and a stainless-steel cylinder, to investigate their temporal wettability behavior. The diagnostics consisted of backlight imaging using a high-speed camera. The droplet spreading was characterized in terms of the droplet base length and the droplet contact angle as a function of time. The study found that the temporal evolution of the contact angle of droplets on dense and porous surfaces is connected to the dynamics of the droplet base. The droplet base undergoes three stages: expanding base, constant base, and finally shrinking base. The study found that for a porous PP membrane, the contact angle decreased exponentially in the initial stage and then linearly over time, indicating the initial dominance of absorption followed later by evaporation. In contrast, dense surfaces exhibit a linear decrease in contact angle, emphasizing pure evaporation with no absorption. A theoretical model for the temporal evolution of the contact angle due to evaporation was developed and the model was successful in correlating the experimental data during the second and third stages. The present study also developed simplified linearized correlations for the temporal evolution of droplets for all three stages. The findings for the time-dependent wetting behavior of PP membranes with micropores demonstrated that even hydrophobic porous materials can become wet due to the liquid's infiltration on the hydrophobic porous surface. [ABSTRACT FROM AUTHOR]

• An optimized, explainable machine learning model to predict shape and drag evolution for a freely moving drop in air. • SHAP analysis enables model explainability and identifies key features affecting temporal changes in drop shape and drag. • Uncertainty quantification for drop shape and drag coefficient using the ensemble method. • Development of reduced-feature models guided by the SHAP analysis. Accurately predicting the shape and drag of a moving drop is crucial in many spray applications. However, due to the complex interaction between the drag force and drop shape deformation, accurate prediction of drop shape and drag from Computational Fluid Dynamics (CFD) simulation requires large computational resources and time. A novel data-driven approach using NARXNN (Non-linear Auto Regressive eXogenous input Neural Network) is proposed in this study, which recurrently predicts the drop shape and drag for a given Weber number (We) and Reynolds number (Re), in the sub-critical We regime where there is no drop breakup. The average error in radius and drag coefficient for the test cases, as low as 0.36 % and 0.49 % , respectively, is achieved. Most importantly, SHAP (SHapley Additive exPlanations) analysis is performed to identify important features for the predictions, hence enabling the explainability of the physics involved in the predictions of machine learning (ML) models for drop deformation and the interaction between the drop and gas flows. Global interpretation of SHAP values identifies We and Re as the most important features to predict the drop shape and drag. Based on the SHAP analysis, several reduced-feature models are developed. All the reduced-feature models can predict drop shape and drag coefficient within 4 % average error in radius and drag coefficient for any We and Re combinations within the prescribed parameter space. The ML models developed in this study demonstrate a tremendous computational advantage over the traditional CFD simulations. The drop shape and drag coefficient evolution can be predicted within seconds for a single case, whereas the CFD simulation takes several days to a week on a single processor. [ABSTRACT FROM AUTHOR]

Paper honeycomb and EPE are widely used in the field of packaging protection and safety transportation. Given the cushioning and protective function of unilateral and bilateral composite layered structures (CLSs) including polyethylene foam (EPE) and paper honeycomb, this work focused on analyzing the energy absorption (EA) and compression deformation of honeycomb thickness (HT) CLS under diverse drop impact (DI) status. Experimental observation showed that the increase of HT can improve the impact resistance of EPE and its CLSs. For the CLS with the HTs of 10, 15, 20, and 25 mm, the increase of paper HT may reduce the EA at low impact energy, while enhancing the EA capability at high impact energy. However, the EA of CLSs with a large HT of 70 mm is relatively poor. For the same drop weight mass or impact energy, the stroke efficiency (SE) and specific energy absorption (SEA) of the unilateral CLS with the same HT are, respectively, increased by 39.1% and 16.2%, so the EA of the unilateral CLS is superior to the bilateral CLS. [ABSTRACT FROM AUTHOR]

Publications on form in popular music have largely assumed the formal sections germane to pop-rock to be the formal designs of "popular music." But the most popular music of our time--music charting on the Billboard Top-40--has absorbed the influence of electronic dance music (EDM) in a way that has fundamentally changed its formal structure. This results in "Top-40 EDM," a genre defined by collaborations between seasoned EDM producers and A-list pop singers. This article begins by defining EDM's three core formal functions (verse, riser, and drop), and compares them to more familiar functions heard in pop-rock music (verse, prechorus, chorus, and postchorus). Part two draws on de Clercq's (2017) concept of blended formal functions to define Top-40 EDM's most recognizable section, the "riserchorus." Part three examines the larger structure of these tracks, including their "compound AAA" forms, in which each of the song's rotations feature the same formal functions, though presented differently. Finally, the article demonstrates how Top-40 EDM producers regularly combine samples at the end of their tracks, resulting in cumulative hyper-blended sections like "riserchorus-bridge" and "riserchorusdrop." [ABSTRACT FROM AUTHOR]

For the first time, the transfer of the substance of a free-falling drop into a resting target fluid at the stage of formation of a primary cavity was tracked by high-speed video recording. In the experiments, water-diluted drops in a ratio of 1 : 100 ink solution or a saturated solution of baking soda with a diameter of cm fell at a velocity of U = 3.1 m/s into water or a 20% ammonium thiocyanate solution in the splash formation mode. In all experiments, the wall of the growing cavity is pierced by thin fibers containing drop material, which form an intermediate fine-structured layer. After the end of the fiber growth stage with a duration of 7–8 ms and diffusion smoothing of the concentration gradients, a liquid layer of intermediate density with a thickness of 1.5 to 0.7 mm is formed around the growing cavity. The layer is separated by a sharp boundary from the target fluid. A new group of inclined fibrous loops is formed in the wake of the collapsing cavity. [ABSTRACT FROM AUTHOR]

Aiming at the problem that the existing rope falling device can only detect the impact force and cannot synchronously detect the impact displacement, this paper introduces a large-range high-precision displacement sensor and constructs a rope impact force-displacement detection device. Taking the nylon kernmantle rope for high-altitude fall protection commonly used in aerial work and rock climbing as the research object, the impact response behavior of the rope when drop mass is dropped once and repeatedly is systematically studied, and the impact force and impact displacement are discussed. Further, the evolution of the elastic modulus of the rope is discussed and this could provide theoretical support for the design of the impact-resistant rope structure and the rope impact protection. [ABSTRACT FROM AUTHOR]

The peculiarities of a liquid viscosity effect on the liquid electrodispersion from the end of capillary through which the liquid is supplied to the discharged system or during the disintegration of a strongly charged drop were studied in an analytical way. It was shown that, upon the electrodispersion of the electroconducting liquid with a low-viscosity, the latter emitted highly charged droplets, initially unstable with respect to their own charge, breaking up into hundreds of even smaller and strongly charged ones, with a corona discharge being ignited around them. As a result, a fan-shaped glow appeared at the top of the liquid meniscus at the end of the capillary or at the top of the decaying charged drop. For the viscous electroconducting liquid, the series of successive disintegrations of the charged daughter droplets were immediately interrupted owing to viscosity damping effect of self-charge-resistant droplets, and no corona discharge glow was formed. [ABSTRACT FROM AUTHOR]

This study was designed to evaluate the ability of Artificial Intelligence (AI) methods including ANN, ANFIS, GRNN, SVM, GP, LR, and MLR to predict the relative energy dissipation (ΔE/Eu) for vertical drops equipped with a horizontal screen. For this study, 108 experiments were carried out to investigate energy dissipation. In the experiments, the discharge rate, drop height, and porosity of the screens were varied. Parameters yc/h, yd/yc, and p were input variables, and ΔE/Eu was the output variable. The efficiencies of the models were compared using the following metrics: correlation coefficient (CC), mean absolute error (MAE), root-mean-square error (RMSE), Normalized root mean square error (NRMSE) and Nash–Sutcliffe model efficiency (NSE). Results indicate that the performance of the ANFIS_gbellmf based model with a CC value of 0.9953, RMSE value of 0.0069, MAE value of 0.0042, NRMSE value as 0.0092 and NSE value as 0.9895 was superior to other applied models. Also, a linear regression yielded CC = 0.9933, RMSE = 0.0083, and MAE = 0.0067. This linear model outperformed multiple linear regression models. Results from a sensitivity study suggest that yc/h is the most effective parameter for predicting ΔE/Eu. HIGHLIGHTS In this study, 108 experiments were conducted to investigate the relative energy dissipation (ΔE/E0) for vertical drops equipped with a horizontal screen.; Intelligent models such as methods including ANN, ANFIS, GRNN, SVM, GP, LR, and MLR are applied to evaluate relative energy dissipation in vertical drops equipped with a horizontal screen.;

Registration of the flow pattern and the matter distribution of a free falling liquid drop in a target fluid at rest in the impact mode of coalescence when the kinetic energy (KEn) of the drop exceeds its available surface potential energy (ASPe) was carried out by photo and video recording. We studied the evolution of the fine flow structure at the initial stage of the cavity formation. To carry out color registration, the observation field was illuminated by several matrix LED and fiber-optic sources of constant light. The planning of experiments and interpretation of the results were based on the properties of the complete solutions of the fundamental equations of a fluid mechanics system, including the transfer and conversion of energy processes. Complete solutions of the system of equations describe large-scale flow components that are waves or vortices as well as thin jets (ligaments, filaments, fibers, trickles). In experiments, the jets are accelerated by the converted available surface potential energy (ASPe) when the free surfaces of merging fluids were eliminated. The experiments were performed with the coalescence of water, solutions of alizarin ink, potassium permanganate, and copper sulfate or iron sulfate drops in deep water. In all cases, at the initial contact, the drop begins to lose its continuity and breaks up into a thin veil and jets, the velocity of which exceeds the drop contact velocity. Small droplets, the size of which grows with time, are thrown into the air from spikes at the jet tops. On the surface of the liquid, the fine jets leave colored traces that form linear and reticular structures. Part of the jets penetrating through the bottom and wall of the cavity forms an intermediate covering layer. The jets forming the inside layer are separated by interfaces of the target fluid. The processes of molecular diffusion equalize the density differences and form an intermediate layer with sharp boundaries in the target fluid. All noted structural features of the flow are also visualized when a fresh water drop isothermally spreads in the same tap water. Molecular diffusion processes gradually smooth out the fast-changing boundary of merging fluids, which at the initial stage has a complex and irregular shape. Similar flow patterns were observed in all performed experiments; however, the geometric features of the flow depend on the individual thermodynamic and kinetic parameters of the contacting fluids.

Interaction dynamics of rigid/deformable particles are included in a wide range of industrial and scientific approaches. The description of the binary collision of particles is required to predict the flow of a concentrated emulsion. The present review introduces the numerical approaches employed to simulate the interaction of two particles and evaluates the impact of deformability, configuration, and flow type on collision dynamics. Two closely interacting drops/bubbles can collide in in-line and side-by-side configurations in Newtonian and non-Newtonian surrounding fluids. Based on the previous investigations, the future trends for the binary collision of deformable particles are provided. [ABSTRACT FROM AUTHOR]

Contact angle hysteresis (CAH) is a significant factor affecting the drop motion on solid substrates. A model of CAH is introduced to explore the influence of CAH on the dynamics of a sessile drop on a uniformly heated surface, and a two-dimensional evolution equation of the drop thickness is established using the lubrication approximation and Navier slip boundary conditions. A numerical simulation is performed to examine the dynamic behaviors of an evaporating drop, and the drop profile, contact angle, contact line, and moving speed are investigated. Simulated results indicate that the drop evolution process involves drop spreading, pinning, and depinning of the contact line. In the drop spreading stage, when the hysteresis angle increases, the spreading period is shortened, and the spreading radius and spreading speed are reduced; in contrast, the pinning period is raised, and the mass of the drop is apparently reduced with increasing hysteresis angle. In the depinning stage, the CAH declines the contact angle, and a flatter pattern is evolved, thereby improving the heat transfer performance, promoting drop evaporation, and shortening the depinning time. The presence of CAH can speed up the drying of the drop, and the large hysteresis angle leads to faster evaporation. Regulating the CAH is an effective way to manipulate the motion of the contact line for an evaporating drop. [ABSTRACT FROM AUTHOR]

Drop motion on a solid surface has many applications in science and engineering, such as in architecture, offshore structures, and electronics. The present paper aims to simulate the motion of a water droplet located on a hydrophobic inclined surface and investigate its deformation rate using ANSYS FLUENT software. The sessile droplet subjected to uniform airflow can be shed depending on the value of drag and drop's adhesion forces. In the present work, coupled level set and volume of fluid method are employed to estimate the motion of the interface. The effect of drop size, wind velocity, drop contact angle, and drop size on the location, velocity, and drop deformation is investigated. The results demonstrate that the drop is splashed as the contact angle decreases. The drop acceleration has an approximately constant trend at Reynolds numbers ranging from 8000 to 80,000. The maximum acceleration corresponds to the hydrophilic surface and is equal to 0.9 m/s2. As the contact angle increases, the acceleration becomes constant. For instance, the drop acceleration is about -0.3 for a contact angle of 135°. The results reveal that the drop requires a longer time to reach the lowest point of the inclined surface by decreasing its diameter and increasing surface hydrophobicity and wind velocity. It is found that as surface hydrophobicity increases, the drop reaches the bottom of the surface in a long time in comparison with the deformed drop. [ABSTRACT FROM AUTHOR]

Coal-water slurries have been actively studied during the last decade due to the fact that much less oxides of sulfur, nitrogen and carbon are formed during their combustion in furnaces of power boilers compared to coal. The main problem that hinders the widespread implementation of such fuels in the energy sector is their long (up to 30-40 s) ignition delay times. Significant (up to 56%) reduction of the ignition delay time is possible when a small (up to 8% by weight) amount of available and relatively inexpensive liquid combustible organic compounds is added to the suspension. The purpose of this work is to substantiate the possibility of significant reduction of the ignition delay times of coal-water fuels by introducing a third component into the coal - water suspension - isoamyl, isopropyl or ethyl alcohol in relatively small (from 3 to 8% by weight) concentrations. Mechanism, characteristics and conditions of ignition of the studied rather promising fuel compositions have been established by the results of experimental studies of ignition process of multicomponent coal-water fuel droplets based on lean coal with alcohol additives in a medium of oxidizer (still air) heated to high temperatures (from 873 K to 1273 K) with recording of heating, ignition and combustion processes by a high-speed video camera (shooting speed up to 105 frames per second). Experiments have shown that stable ignition delay time of the studied suspensions based on lean coal decreases by 11-56% with an increase (from 3 to 8%) in the mass concentration of one of the alcohols in the composition of coal-water fuel at the initial characteristic size of droplets from 1.0 to 2.5 mm. Each studied composition was compared with conventional coal-water fuel burned under similar conditions. Increase in the mass concentration of alcohol in the composition of coal-water fuel reduces the value of the flash point by 27-30%. The viscosity of alcohol-coal-water fuels increases by 7.0 to 40% when the researched alcohols are added to the coal-water slurry. Influence of mass concentration of isoamyl, isopropyl and ethyl alcohols in the composition of coal-water fuel on the characteristics of initiation of ignition and combustion processes established in experiments justifies the possibility of sufficiently effective application of such three-component suspensions in the power industry. Necessary and sufficient conditions for the ignition of alcohol-coal-water fuel droplets have been established based on a mathematical model and experimental data. Increase in the cost of such fuels has been analyzed in comparison with conventional coal-water slurry. It has been shown that the most attractive from the energy and economic points of view is coal-water fuel with isoamyl and isopropyl alcohols in the composition. The obtained results are of significant practical value, as they illustrate the possibility of achieving optimal ignition and combustion conditions for promising multicomponent coal-water suspensions with alcohol additives in the furnaces of boiler plants. [ABSTRACT FROM AUTHOR]

The article discusses the principles and possibilities of using jet-drop optical measuring systems for monitoring the electric field strength (EFS). Two applied techniques are considered. First, the deflection of flying charged droplets (balls, hollow granules) used as micro-objects sensitive to EFS and deviating from a given rectilinear trajectory of motion, like an electron in a kinescope. Secondly, stroboscopic determination of the position and/or displacement of drops by pulsed illumination of the side of the deflected drop by the optical flow and measurement of the reflection angle for it. The possibilities of implementing the differential method of EFS measurements are discussed. The features of the use of liquids with the addition of metal nanopowders or based on liquid metals, as well as hollow droplets in the form of microspheres or hollow granules are considered.

The shape evolution of a subsiding splash of a freely falling drop (the diameter is D = 0.42 cm, and the contact velocity is U = 3.1 m/s) in the mode of active generation of sound packets was traced by high-speed video recording. The shape of the splash is continuously transformed as it spreads. During the formation of the second cavity, the splash base pinches off the depression bottom of the deformed surface of the target fluid. A third cavity is formed when the top of the splash is immersed. A returning droplet, which has previously flown out from the top of the splash and which by its lateral surface is in contact with the walls of the remnant of the third cavity, forms the fourth cavity. The shape of the last cavity is distorted by thin flows that are accelerated by the fast conversion of the available potential surface energy (APSE) when the free surfaces of the merging fluids are eliminated. A rupture in the base of the subsiding splash was observed in all experiments of this series. [ABSTRACT FROM AUTHOR]

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

The so-called Rayleigh-Plateau instability of fluid jets has been widely studied and is extensively used in the Continuous InkJet (CIJ) printing process. The present dataset contains the numerically-generated interfaces of Newtonian fluids jets in CIJ jetting conditions for low to moderately high stimulation amplitudes. We used Basilisk, an open-source Computational Fluid Dynamics (CFD) software specialized in multiphase flow to compute thousands of jets of fluids for Reynolds numbers ranging from 100 to 1000. The dataset gives raw data of CFD simulations liquid-air interfaces, for each Reynolds – stimulation amplitude pair. The present 10 GB dataset contains ≈110000 interfaces which allows to use novel machine learning and deep-learning approaches to explore jet morphologies evolution that can’t be addressed with the classical Rayleigh’s theory.

Biological systems, by nature, are highly complex. These systems exhibit diverse hierarchical spatial and temporal features when driven far from equilibrium. The generated features are susceptible to the initial conditions that largely depend on vast parameter space. Extracting information on their properties and behavior thus becomes far too complex. This work seeks to examine the drying kinetics of the drops containing a globular protein (lysozyme (Lys)), phosphate buffer saline (PBS), and thermotropic liquid crystal (LCs). The drying evolution and the morphological crack patterns of these drops are examined using high-resolution microscopy, textural image analysis, and statistical methods. This study observes that the textural parameters can identify the (i) phase separation of the salts present in the PBS and (ii) the LCs' birefringence during the drying evolution. This birefringence activities of the LCs slow down when the initial PBS concentration is increased from 0.25 to 1× despite using a fixed volume of LCs. To comprehend such a surprising effect, the combinations of (i) Lys+PBS and (ii) PBS+LCs are thoroughly examined. A phase diagram is established as a function of initial concentrations of Lys and PBS. The scanning electron microscopic images of Lys+PBS reveal that the tuning between lysozyme and salt concentrations in PBS plays a significant role in determining the morphological patterns. The Lys drops with and without LCs exhibit two distinct regions: the peripheral ring ("coffee-ring") and the central ones. This phase-separated ring formation indicates that the film containing Lys and salts might have formed on top of these LCs in the central region, which reduces the optical response (birefringence) of LCs. A physical mechanism is proposed in this paper to anticipate the redistributions of LCs in a multi-component system such as Lys+PBS+LCs. [ABSTRACT FROM AUTHOR]

The evolution of the distribution pattern of an ink droplet freely falling on the wavy surface of a liquid is traced by video-recording methods. A system of travelling plane gravity–capillary waves with a frequency of Hz (a wavelength of cm) was created by a vertically oscillating pointed strip. Drops of alizarin ink with diameter cm fell freely from the dispenser and reached contact velocity cm/s in the mode of splash formation. In the phase of primary contact and coalescence, the colored drop spreads in agitated liquid like in a quiet medium with the formation of a cavity with its bottom covered by colored fibers, a crown, and a splash. The growing crown is surrounded by a group of thin radial trickles with vortex heads and separate spots (wakes of earlier returned ejected droplets). Subsequently, the colored liquid on the surface is divided into three independently moving formations: a finely structured area of primary contact of an irregular shape, a submerging vortex ring, and a near-surface vortex dipole. In all components of the flow, the dye is distributed in the form of thin fibers for a long time until the final phase of erosion by residual flows and molecular diffusion processes. The geometry of movement and the general structure of the separated colored areas are traced. [ABSTRACT FROM AUTHOR]

In more developed countries significant changes have occurred in the ways in which risks are viewed, so much that the prevailing view has shifted from a mere concentration of vulnerability reduction towards increasing resilience against disasters. On this basis, risk reduction programmes should seek the creation and reinforcement of resilient communities. Due to its particular natural and geographic conditions, Tehran has been vulnerable against a series of shocks including earthquakes, floods etc., rendering the attention to the concept of resilience all the more necessary. The present paper views the measurement of resilience in Tehran using indicators, and the offering of an investigation method, as a first step towards making the city more resilient. This is done here based on Tehran districts’ 2001 statistical data, using ‘Baseline Resilience Indicators for Communities’ (BRIC) methods, and with a focus on a series of indicators based on amended ‘Disaster Resilience of Place’ (DROP) model as presented by Cutter et al. A conceptual model is made on this basis, and used to calculate a combined resilience indicator using ‘Fuzzy Analytic Network Process’ (F’ANP), which is comprised of factor analysis and ANP network model. After accurately defining the conceptual model through affirming factor analysis according to resilience levels, Tehran’s 23 resilience indicators were determined under six categories socio-economic, public service accessibility, infrastructural-social, open space (infrastructural), activity-economic, and infrastructural. These factors and their indicators were then used to process F’ANP analytical model. This significance factor was then combined with arithmetic combination method, and eventually the resilience combined indicator was worked out, and then applied to Tehran districts. The results show higher resilience levels for the northern half of Tehran compared to its southern half.

The basic effects and their combinations on evaporated liquid located on solid surface and in the form of a suspended droplet are analyzed. Methods of applying these effects for liquid evaporation under the following boundary conditions of the liquid location: «drop», «film» are considered. The classification of one-, two-, and three-factor effects on the evaporated liquid is proposed. The direction of further research in the field of joint application of convective, conductive and vacuum influences on the dried object is formulated

The evolution of the shape of a sequence of cavities accompanying the coalescence a freely falling drop with a liquid at rest is traced by the method of high-speed video recording. The flow is visualized by the dark field method in the side view (the line of sight lies on the free surface), as well as in the LED-based backlight. In the first case, LED sources were installed on top and on the side of the transparent cuvette; in the second case, a spotlight located behind the cuvette was added to the LED sources. For the first time, the high-resolution experimental technique allows registering the bottom oscillations of the secondary cavities and visualizing the groups of gas bubbles, including frozen-in ones, which reproduce the initial shape of the rapidly filling second cavity, which is formed during splash coalescence. The next shallow cavity is formed after the splash top is submerged. The last cavity is formed by a returning drop previously ejected from the top of the splash. An increase in the rate of the collapsing cavity depth is associated with the conversion of the available potential surface energy (APSE) with a decrease in the area of the free surface of the fluid. [ABSTRACT FROM AUTHOR]

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The terminal settling velocity (TSV) calculation of drops and other spherical objects in fluid medium is a classical problem, which has important application values in many fields such as the study of cloud and precipitation processes, the evaluation of soil erosion, and the determination of fluid viscosity coefficient etc. In this paper, a new explicit approximation model of TSV is established, which combines the theoretical solution of N-S equation about fluid motion around spherical objects and the statistical regression of solution dimensionless coefficients with measurement data. This new model can adapt to different values of drop parameters and medium parameters in a large range of Re. By this model, the relative and absolute calculation errors of TSV are in range of −3.42%−+ 4.34% and −0.271 m/s−+ 0.128 m/s respectively for drop radius 0.005−2.9 mm. Their corresponding root mean square values are 1.77% and 0.084 m/s respectively, which are much smaller than that of past theoretical and empirical models. [ABSTRACT FROM AUTHOR]

The paper is dedicated to reducing the technogenic impact on the environment of using highly efficient apparatus for the complex exhaust gas treatment, operating in the advanced turbulence regime – an apparatus with a regular pulsating nozzle (RPN). Devices with on-load tap-changers are characterized by high efficiency of capturing solid particles of different dispersion (e.g., fog, dust, and smoke), the possibility of self-cleaning of contact elements from sticky dust, low material consumption, and high reliability in operation. Purpose of the study – to obtain analytical solutions for assessing the efficiency of capturing polydisperse aerosols in an apparatus with an on-load tap-changer due to diffusion and inertial mechanisms. The paper proposes a new solution for the minimum effective diameter of aerosol particles that can be captured in devices with an on-load tap-changer and can be used for a wide range of diameters of absorbing liquid droplets and their number in the volume of the apparatus. The calculations allow us to say that the minimum effective diameter of aerosol particles captured by liquid drops in an apparatus with an on-load tap-changer is less than 0.3 microns.

We consider a sequence of four variable polynomials by refining Stieltjes's continued fraction for Eulerian polynomials. Using combinatorial theory of Jacobi-type continued fractions and bijections, we derive various combinatorial interpretations in terms of permutation statistics for these polynomials, which include special kinds of descents and excedances in a recent paper of Baril and Kirgizov. As a byproduct, we derive several equidistribution results for permutation statistics, which enables us to confirm and strengthen a recent conjecture of Vajnovszki and also to obtain several companion permutation statistics for two bistatistics in a conjecture of Baril and Kirgizov. [ABSTRACT FROM AUTHOR]

For the first time, the process of merging a drop of ferric chloride solution (concentration 16 and 1%) with a solution of ammonium thiocyanate (20%), including the formation and restructuring of a system of inclined loops on the surface of the cavity, visualized by the products of a chemical reaction, was recorded on video. The brightly colored iron thiocyanate solution formed during the merging of liquids lands into primary contact droplets and groups of subsequent splashes. Fibers containing iron thiocyanate form linear and mesh structures on the walls of the cavity and crown. Ledges and small annular legged vortices are formed at the bottom of the cavity, under the mesh nodes. During the cavity collapse, the ledges extend into inclined loops up to 4.6 mm long, which penetrate into the target fluid. As the flow evolves, the fibers rearrange, forming new structures. Finely colored areas persist for a long time and spread out under the influence of diffusion processes. [ABSTRACT FROM AUTHOR]

The results of experimental studies on the properties of a capillary liquid bridge in the gap between two glass spheres of an equal diameter are presented. It is shown that for the case when the diameter of the spheres is much larger than the capillary scale of liquid, the shape of the capillary liquid bridge can be described as a figure formed by two "drops", touching the spheres, and the central catenoid. The contact angle between the "drop" and the sphere depends on the effective mass of the "drop", and the relative position of the catenoid and the "drops" is set by the condition that the contact angle between them is equal to zero. In the field of gravity, the position of the minimum cross section of the catenoid does not coincide with the middle of the gap between the spheres and is determined by the magnitude of the surface energy and the way how the mass of liquid in the bridge is distributed over the "drops" and the catenoid. [ABSTRACT FROM AUTHOR]

Purpose. In addition to characterizing the optical, electronic, mechanical, and catalytic properties of individual nanoparticles, much attention is paid to the development of methods for assembling nanoparticles into large ordered or disordered superstructures. These assembly methods are based on many different types of interparticle interactions (Van der Waals, magnetic, electrostatic, molecular dipole, covalent and hydrogen bonds). Recently, the drip method has been used to study early structural formation in colloidal systems. When particles interact in a drying drop, depletion forces must be taken into account. In this paper a model experiment has been carried out to study the effect of depletion forces on phase formation during the drying process of a drop. Methods and methodology. Colloidal suspensions of Aerosil at a concentration of 0.1 mg / ml with a particle size of 100 nm and polystyrene latex with a particle size of 20 nm at a concentration of 10 mg / ml were used as starting materials. Homogeneous colloidal suspensions of a given concentration were prepared using an ultrasonic disperser UZG-13. The particle sizes of the resulting suspensions were controlled by light scattering on a Photocor mini particle size meter. A comparative analysis of the drying process of a droplet with the initial components and with their mixture has been conducted in dynamic mode. The experiments were carried out in standard conditions. A digital optical microscope Bresser Advance ID was used to control the drying dynamics. The morphology and identifi cation of the drying products have been carried out by a set of methods, including IR spectroscopy - Bruker VERTEX 70, scanning microscopy - Jeol JSM-6380LV and transmission microscopy - LIBRA 120 PLUS. Results. When a droplet of a mixture of aerosil and latex was dried, there was observed the formation and rapid growth of a new phase of microscopic sizes up to ten microns in a matter of tens of seconds. The color of the solution changes sharply from transparent light blue to bright blue. The formation of a new phase is localized in the central region of the drop. According to the data of IR spectroscopy and of electron and transmission microscopy, the resulting phase is crystalline SiO2. To interpret the obtained results, a computational experiment was carried out in a statistical model system of rigid non-interacting spheres in the Broun motion approximation. In the simulation the spatial redistribution of large particles in the presence of small particles is observed, leading to the occurrence of the thickenings. Phase formation is interpreted as the result of the action of the nonequilibrium depletion force under the conditions of the hydrodynamic instability of a drying drop. Conclusions. In the conditions of a model experiment on phase formation during drying of a drop of a non-interacting particles colloidal solution in the aerosil-polystyrene latex system, the formation and rapid growth of a new phase of crystalline SiO2 has been detected. The phase formation process is accompanied by a sharp change in the color of the solution from light blue to blue. The crystallite size varies from ten nanometers to ten microns. A diffraction pattern of the new phase has been found indicating its crystalline nature.

Mat Johnson’s first work, Drop (2000), explores the themes of the American Dream and Nightmare in relation to issues of racial and national identity, racial inequality, and personal growth. The protagonist, a poor but talented African American man, decides to expatriate to England to chase the dream which he is denied at home. When his English Pygmalion dies, he is forced to return to the US and face the nightmare of racism, exclusion, and fear. However, he has also the chance to reconcile with his community, which will eventually help him leave the country again. This paper analyses Johnson’s use of the theme of expatriation in light of Michel Foucault’s concept of heterotopia and argues that, through heterotopia, the author is able to enact a decentring strategy which undermines national ideology and focuses on the active role played by the Black community in its members’ self-improvement.

Emulsion formation is of great interest in the chemical and food industry and droplet breakup is the key process. Droplet breakup in a quiet or laminar flow is well understood, however, actual in-dustrial processes are always in the turbulent flow regime, leading to more complex droplet breakup phenomena. Since high resolution optical measurements on microscopic scales are extremely dif-ficult to perform, many aspects of the turbulent droplet breakup are physically unclear. To over-come this problem, scaled experimental setups (with scaling factors of 5 and 50) are used in con-junction with an original scale setup for reference. In addition to the geometric scaling, other non-dimensional numbers such as the Reynolds number, the viscosity ratio and the density ratio were kept constant. The scaling allows observation of the phenomena on macroscopic scales, whereby the objective is to show that the scaling approach makes it possible to directly transfer the findings from the macro- to the micro-/original scale. In this paper, which follows Part I where the flow fields were compared and found to be similar, it is shown by breakup visualizations that the turbulent droplet breakup process is similar on all scales. This makes it possible to transfer the results of detailed parameter variations investigated on the macro scale to the micro scale. The evaluation and analysis of the results imply that the droplet breakup is triggered and strongly influenced by the intensity and scales of the turbulent flow motion. [ABSTRACT FROM AUTHOR]

Portrayals of sexualized narratives are rife in ethnographic accounts of Electronic Dance Music (EDM), where the visceral musical and haptic experiences of dancing to club music are intertwined in a tantalizing symbiosis. This is music that is habitually understood through erotic semiosis: protracted build ups of stimulation and intensity, layer upon layer of musical repetition being added in service of arousal, and a teasing denial of harmonic and sonic resolution are expanded and amplified, until there is a final fulfilment granted by the DJ at the moment of the “drop”. Bringing together musicological discussions of climax with socio-psychological and neurological research on the orgasm, this article explores the manifold ways in which technologies of arousal in dance music mediate the sexual space of the dancefloor and consider how metaphors of pleasure and fulfilment are actualised in EDM in ways which destabilise the prevalent body of heteronormative, male-focussed narratives around stimulation and arousal.