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The behavior of a liquid drop placed on an oscillating solid substrate is studied. The vibrations are normal to the plane of the substrate. The amplitude of the vibrations is assumed to be small compared to the radius of the drop, and the vibration frequency is suppose to be much larger than the frequencies of the natural oscillations of the drop shape. The effect of vibrations on the drop shape is studied for a small values of the vibration parameter equal to the ratio of the vibration pressure to the capillary pressure. It is assumed that the drop surface in the absence of vibrations is hemispherical. Under the influence of vibrations, the drop height decreases and the base area increases. In this case, the surface deformation changes proportionally to the vibration parameter. At finite values of the vibration parameter, the quasi-equilibrium shape can differ significantly from spherical. In this case, the problem for pulsations is solved numerically using the boundary element method. To determine the average shape of a drop at finite values of the vibration parameter, the variational principle is used. The obtained results are in good agreement with the solution in the limit of small values of the vibration parameter. With an increase in the vibration parameter, the average contact angle decreases, the area of the base area increases, and the height decreases. [ABSTRACT FROM AUTHOR]

Disperse systems, and emulsions in particular, are currently massively used in fields as varied as food industry, cosmetics, health care and environmentally‐friendly materials. To meet increasingly precise needs or targeted applications, these systems need to be endowed with new functionalities at their interfaces, in addition to their composition and structural properties. However, due to the fragility of drops and the low reactivity of their surface, conventional solid surface chemistry cannot be used for such a purpose. Several specific emulsion interface functionalization techniques have thus been developed for targeted systems and applications, but a general framework has yet to be drawn. In this review, we attempt to present these methods in a unified way through the prism of what we may call “liquid surface chemistry”. We propose to categorize existing methods into drop‐coating strategies, including layer‐by‐layer techniques and polymer coating, with a particular focus on polydopamine, and emulsifier‐carrier approaches involving particles and/or amphiphilic molecules. They are discussed in a transversal way, highlighting the underlying physico‐chemical principles and providing a comparative analysis of their advantages, current limitations and potential for improvement. We also propose future directions and opportunities, involving for instance DNA‐based programmability or artificial intelligence, which could make liquid surface chemistry more versatile and controlled. [ABSTRACT FROM AUTHOR]

A mathematical model is presented to predict the shape of an evaporating droplet with a pinned contact line, and the axisymmetric time-dependent fluid flow inside. We consider the diffusion-limited evaporation regime, where the evaporative flux diverges at the contact line. To regularize this singularity, the droplet domain is divided into two regions: (i) a wedge at the contact line and (ii) the remaining drop. Near the contact line, the flow is characterized by solving Stokes equations analytically in a wedge. Away from the contact line region, lubrication theory is used. The drop and wedge regions are connected via boundary conditions preserving continuities of mass and drop shape. We show how the proposed model reasonably predicts experimentally observed evaporation rates and contact angle dynamics for small initial contact angles. In addition, the work demonstrates that removal of the diverging evaporative flux near the contact line, as done in prior works to address the singularity, can significantly affect the predicted drying droplet dynamics. [ABSTRACT FROM AUTHOR]

Warhead drop safety involves multiple aspects such as explosive formula, charging process, warhead design, and service environment. The literature on the warhead drop safety of conventional weapon ammunition was comprehensively summarized, and the current status of warhead drop safety was systematically analyzed from five aspects: research on typical explosive impact sensitivity, dynamic mechanical properties of typical explosives, theoretical research on non-impact ignition of warhead charge drops, warhead drop testing and simulation research, and evaluation methods and standards for warhead drop safety. In addition, some suggestions on the drop safety study of mine warheads were put forward. The analysis results in the article could provide a reference and guidance for the research on the drop safety of mine warheads.

The splashes of a highly viscous fluid (glycerol) resulting from its pulsed displacement from a gap between two rapidly approaching disks are studied. It is found that, outside the disks, the splash has the form of a thin film bounded by an annular rim. A physical model of the splash is formulated, and analytical solutions describing its trajectory are given. The calculation results are compared with experimental data. The effects of fluid viscosity, surface tension, and film breakdown are analyzed. It is shown that the key influence on the splash development scenarios is exerted by surface tension of the film connecting the rim to the disks. [ABSTRACT FROM AUTHOR]

The available experimental data focusing on the differences between bubble and drop breakages are still scarce in the literature. This work conducts the experiments of single bubble and single drop breakages in agitated turbulent flows. The effects of fluid particle size and agitation speed on daughter fragment number, breakage time, breakage probability, breakage frequency, and daughter size distribution (DSD) are analyzed. The breakage frequencies of bubble and drop show the monotonic and non‐monotonic variation trends with increasing fluid particle size, respectively. The variations of bubble and drop DSDs exhibit opposite trends, the probability of equal‐sized breakage of bubble increases while that of drop decreases when agitation speed or fluid particle size increases. These different trends cannot be predicted by most of the existing models simultaneously. The processes of elongation and internal flow redistribution during deformation may be the important factors causing these differences. [ABSTRACT FROM AUTHOR]

The results of experimental studies of the cocombustion of coal–water fuel with fuel oil are presented. According to the results of experimental studies, the efficiency of joint ignition of stationary single droplets of coal–water fuel and fuel oil was substantiated. A decrease in the ignition delay times of fuel droplets was found in comparison with the ignition of only coal–water fuel droplets under identical conditions. A significant decrease in the ignition delay times of coal–water fuel droplets is typical for droplets with sizes of 2 and 3 mm in the entire studied temperature range of the oxidizer (from 873 to 1,273 K) and distances (from 2 to 4 mm) between drops of coal–water fuel and fuel oil. It has been experimentally established that the reduction of ignition delay times is 58 and 70%. For droplets of coal–water fuel with a characteristic size of 1 mm, the changes in ignition delay times are ambiguous. The joint combustion of coal–water fuel and fuel oil affects the ignition of droplets of coal–water fuel, and the characteristic size of which is more than 1 mm. With this method of burning coal–water fuel and fuel oil, the latter acts as a catalyst when igniting coal–water fuel, thereby ensuring a stable combustion of such fuel. The combustion of two-component coal–water fuel together with fuel oil can avoid the problems typical of such fuels: reduce the requirements for spraying devices, solve the problem of low reactivity, increase the completeness of combustion of this fuel, and fully use it in the production of thermal and electrical energy. [ABSTRACT FROM AUTHOR]

South Korea is one of the leading markets for the e-commerce industry. In line with the rapid growth of the e-commerce industry, the parcel delivery volume in Korea has also proliferated. Despite the developments in the Korean e-commerce and courier industries, consumers still experience a high package damage rate. In response, many packaging engineers in Korea have raised the need for new parcel shipping environment tests that reflect the Korean ground shipping environment in order to properly optimize packages. However, only limited information on the Korean parcel shipping environment is currently available. Therefore, this study focused on measuring and analyzing the shock and drop levels that parcels experience during ground shipping in Korea. Shock data were collected from a total of sixty one-way shipments for small, lightweight packages and medium, mid-weight packages. The findings revealed that the two types of boxes do not experience significantly different numbers of shock events or drop heights in the Korean parcel delivery environment. Furthermore, the number of shock events that occur in Korea is substantially less than the international testing standard and less than in previous studies conducted in both Europe and the USA. In contrast, however, the drop heights are higher than those in the international testing standard and previous studies. Shock events were found to occur most frequently on the edges and to be concentrated around the bottoms of the packages. Most shock events happen while packages are loaded and unloaded at hub terminals and sub terminals. [ABSTRACT FROM AUTHOR]

The collision of drops of water and elastic liquids with a thin cylinder (fiber) has been studied. Aqueous solutions of polymers were used as elastic liquids, which simulated the rheological behavior of oral fluid—the main carrier of infections by airborne drops. Water as a Newtonian fluid was investigated to identify the elastic effects when comparing the collisions of Newtonian and non-Newtonian fluids—water and polymer solutions. The flight path of the drop and the cylinder axis are mutually perpendicular. Attention is focused on the difference between the collisions of water drops and drops of elastic liquids. In the experiments, the diameter of the drop was 3 mm, and the diameter of the horizontal stainless-steel cylinders was 0.4 and 0.8 mm. Drops were formed by the slow flow of liquid from a vertical stainless-steel capillary with an outer diameter of 0.8 mm, from which the drops were periodically separated under the influence of gravity. The velocity of the drop before the collision was determined by the distance between the end of the capillary and the target (cylinder); in the experiments, this distance was 5, 10, and 20 mm. The velocities of falling drops before impact were estimated in the range of 0.2–0.5 m/s. The collision process was monitored using high-speed video recording methods with frame rates of 240 and 960 Hz. Water and aqueous solutions of polyacrylamide with a molecular weight of 11 million and concentrations of 100 and 1000 ppm were used as test liquids. Experiments have shown that, depending on the height of the drop and the concentration of the polymer, various drop collision scenarios are possible: (1) short-term rebound of the drop from an obstacle, (2) braking and stopping the drop on the obstacle, (3) flow of the drop around a cylindrical obstacle while maintaining continuity and continuing free flight, (4) disintegration of the drop into two secondary drops, each with its own history of subsequent flight. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Angiología is the property of Publicidad Permanyer SLU 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.)

Understanding multiphase flows with phase change is of fundamental importance for the optimal design and operation of polymer processing. However, the study of multiphase flows with phase change is challenging in practice because polymers have complex physical properties and it is difficult to obtain precise thermal-hydraulic measurements of multiphase flows with phase change due to the high temperatures involved in polymer processing. Computational simulations overcome many of these difficulties and thus provide an essential alternative to study intricate thermal-hydraulic mechanisms not easily observed in a laboratory setting. In this article, I review the current state-of-the-art as well as outstanding challenges in the study of multiphase flows with phase change in polymer processing through the author's computational studies on the motion of bubbles and drops with phase change. [ABSTRACT FROM AUTHOR]

The Stokes axisymmetric flow of an incompressible micropolar fluid past an another immiscible micropolar fluid sphere is studied analytically under small Reynolds numbers. A spherical coordinate system is used to solve the Stokes equations for the fluid velocities, pressures and microrotation vectors inside and outside the micropolar fluid drop. The boundary conditions on the micropolar fluid drop surface are satisfied by vanishing of a normal component of velocity inside and outside the micropolar fluid sphere, tangential components of velocities are continuous, tangential components of stresses are continuous, and the microrotation vector inside and outside the micropolar fluid sphere vanishes. Numerical results for the drag force acting on the micropolar fluid drop are obtained for various values of the relative viscosity of the fluid drop, micropolar parameters (vortex viscosity parameters), and shear spin viscosity parameters. It is found that the drag force exerted on the viscous drop in a micropolar fluid and the micropolar fluid drop in a viscous fluid increase with an increase in the viscosity ratio. Additionally, the findings demonstrate that the drag force acting on the micropolar drop in a micropolar fluid increases as the viscosity ratio increases, and the drag force on the gaseous bubble is less than that of a solid sphere. Well-known results are reduced, and comparisons are made with a classical viscous-viscous droplet, a micropolar-viscous droplet and a viscous-micropolar droplet. The present study has significant applications in natural, biological, and industrial processes, such as sedimentation phenomena, liquid-liquid extraction, the study of blood flow, and the rheology of emulsions. [ABSTRACT FROM AUTHOR]

Copyright of University of Sharjah Journal of Law Sciences (JLS) is the property of University of Sharjah - Scientific Publishing Unit 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.)

A mathematical model is constructed for the dynamics of a raindrop moving in a gravity field through an atmosphere containing fine particles, taking into account the processes of relaxation of its velocity and the capture of fine particles. It has been established that the equation of motion of a drop in the problem being posed belongs to the class of singularly perturbed equations, for the integration of which it is necessary to involve special algorithms. In the limiting modes of droplet motion, analytical solutions of the problem are obtained that describe the dependence of the droplet velocity and coordinate on time. In the complete formulation, the solutions of the problem are obtained numerically for different values of the defining parameters. The influence of the droplet size on the parameters of its motion in a concentrated aerodispersed mixture has been studied. The dependences of the limiting volume fraction of the solid component in the composition of the drop and the intensity of the precipitation of particles (washed out by the drop) on the earth's surface on the size of the drop are obtained. A comparison of the calculated, approximate–analytical and experimental dependences of the steady-state rate of fall of a drop on its size has been carried out, and it shows their good agreement. [ABSTRACT FROM AUTHOR]

Relevance. An analysis of the current state of the global energy agenda shows that the problem of anthropogenic impact on the planet’s atmosphere by thermal energy facilities is one of the most important for humanity. At the same time, the growth in electricity consumption stimulates the introduction of ever new power generating capacities. For a long time, it was believed that the solution to this problem was the large-scale introduction of non-traditional renewable energy sources (wind generators and solar panels) into the overall balance of electricity generation. However, it is now becoming obvious that renewable energy sources cannot fully cover all electricity needs. The latter creates incentives for the commissioning of new thermal power plants, usually operating on coal fuel. But the main problem of coal energy – its anthropogenic impact – still remains unresolved. This situation creates the prerequisites for the development of new “clean” coal technologies with a full cycle of sequestration of combustion products. One of the most promising technologies for burning coal with low emissions is the combustion of coal in the composition of coal-water fuel. However, coal-water fuel technology has a number of disadvantages. One of the most significant is the high ignition delays of typical (with a characteristic size of 3–5 mm) droplets of coal-water fuel. One of the most promising methods for solving this problem is spraying coal-water fuel in an ultra-fine state (with a characteristic droplet size of 0.1–1 mm). Aim. Experimental study of the conditions and characteristics of crushing droplets of coal-water fuel in a high-speed air flow. Object. Coal-water fuel prepared on the basis of lean coal. Method. Special experimental stand to establish the main characteristics and conditions of dispersion of coal-water fuel droplets. Results. The results of experimental studies show that for stable fragmentation of typical droplets of coal-water fuel, the speed of the latter (during the spraying process) must be at least 40 m/s.

Thermocapillary drop migration is driven by surface tension gradient. On an inclined plane, gravity acts as an additional force that can have a promoting or resisting effect depending on the thermal gradient direction. The present 2-D model extends Brochard and Chebbi models for thermocapillary migration of small drops on horizontal plates by accounting for Marangoni and Poiseuille flow components, while including the effect of gravity, acting in the case of inclines. The present treatment is based on fundamentals of conservation of mass and momentum transport, and uses the lubrication approximation and extended boundary conditions at the receding and advancing contact lines. A model for the dynamics of migration is provided, and an analytical solution is derived for drop migration dynamics and the critical angle of inclination.

Varroa destructor mite poses a serious problem for the future of bee populations around the world. Today, there are many commercial drugs with the same and different active ingredients on the market to chemically control over of Varroa destructor. More frequent chemical applications for against Varroa destructor increases stress resilience, colony losses, loss of yield and residue problems in bee products. The scope of this project is aimed to determine the appropriate control method of Varroa by investigating the efficiency values of the evaporation and dropping methods of Oxalic acid. Experimental area were chosen three different apiaries. 28 colonies were determined in each apiary and equalization studies (area with brood, number of bees with bees, age of queen bees, honey, pollen, etc.) were carried out in these colonies. The determined colonies were randomly divided into 4 groups as 7 colonies. The first group is the control group, the second group is applying 2 g of oxalic acid by vaporizing, the third group is 4% oxalic acid 5 ml of sugar syrup (1:1) is dropped between the frames, and in the fourth group, the fight against a drug that is determined by the beekeeper in the market without interfering with the beekeeper. In order to evaluate the data, samples were taken for four periods, before and after spraying in spring and autumn. While the varroa measurements in the group of syrup, vapor and spraying were found to be statistically less than the control group, the syrup, vapor and spraying groups were statistically similar in terms of varroa measurements. Oxalic acid syrup application showed higher efficiency in spring and autumn than vapor application. There is no statistically difference between both two-application method reveals that it can be used as an effective and safe alternative to chemical control against varroa.

The Rayleigh-Plateau instability, a phenomenon of paramount significance in fluid dynamics, finds widespread application in the Continuous InkJet (CIJ) printing process. This study presents a comprehensive dataset comprising experimental investigations of fluid jet breakup phenomena under large-amplitude stimulation conditions using an industrial CIJ print-head from Markem-Imaje. Unlike previous studies, this dataset encompasses a diverse range of experimental conditions, including nine different Newtonian fluids with meticulously measured rheological properties (viscosities, surface tensions and densities). The applied stimulation amplitudes vary from 5V to 45V, representing a substantial span of excitation levels.The experimental setup captures the intricate dynamics of fluid jets subjected to these varying conditions, producing a rich collection of over 5,000 high-resolution images depicting the breakup phenomena. Each amplitude of stimulation and fluid type yields more than 55 distinct images, providing detailed insights into the evolving jet morphologies.To ensure the accuracy and relevance of the dataset, all ejection parameters are rigorously documented and included. The dataset thus serves as a valuable resource for researchers seeking to explore the dynamics of large-amplitude Rayleigh-Plateau instability in CIJ printing. Its comprehensiveness and diversity make it particularly suitable for the application of novel machine learning and deep-learning approaches, enabling the study of jet morphological evolution beyond the confines of classical Rayleigh's theory. This dataset holds promise for advancing our understanding of fluid jet dynamics and enhancing the efficiency and quality of CIJ printing processes.

Experiments have identified two modes of coalescence of a free-falling drop of liquid mixing with a deep target fluid at rest–a slow intrusive mode and a fast impact mode. The influence of the energy transfer and transformation processes on the flow dynamics and structure is analyzed. Experimental planning and data interpretation were carried out subject to the properties of complete solutions to the system of fundamental equations of inhomogeneous fluid mechanics. The transfer of the results to flows in facilities and in the environment is discussed. [ABSTRACT FROM AUTHOR]

Acoustic signals have been studied by coordinated optical and acoustic methods in two modes of a free-falling water drop merging with water. Only the primary sound packet is observed in the intrusive mode at a low drop velocity when a cavity is formed with a delay in the colored wake of the inflowing liquid. The influence of the drop velocity on the parameters of the primary signal was traced in the experiments. The cavity begins to form from the moment of initial contact when the drop velocity is high. The flow pattern becomes more complicated, the drop substance is distributed over the surface of the emerging cavity and growing crown in the form of individual fibers forming linear and reticular structures. The falling section of the primary signal is constituted by a group of pulses with a complex spectral composition. Further, after a pause, one or more low-frequency sound packets are recorded. The spectral portrait of the secondary packets is related to the shape of the detached gas cavity. A smooth axisymmetric cavity radiates a monochromatic packet. A complex-shaped cavity transforming into a gas bubble emits a multi-frequency signal. The duration and amplitudes of the secondary sound signals depend on the rate of transformation of the separated gas cavity into a smooth spheroidal bubble. The parameters of acoustic signals change non-monotonically with increasing velocity of the merging drop. [ABSTRACT FROM AUTHOR]

High-speed video recording was used to trace the matter transfer pattern of a free-falling water drop and of the deformation of the free surface of the target fluid at the intrusive mode when the available potential surface energy (APSE) exceeds the kinetic energy of the drop. The free surface of the unified drop-target fluid system remains convex at the initial submerging stage. The inflowing drop forms a lenticular intrusion in the fluid bulk, which gradually transforms into a vortex ring. A cavity begins to form with a time delay Δt = 10 to 12 ms. The cavity surface includes traditional flat, spherical, cylindrical and conical sections moving at different velocities. The temporal variability of the intrusion and cavity geometry was traced. The drop substance is preserved as individual fibers in the wake of the submerging ring. [ABSTRACT FROM AUTHOR]

Copyright of Ingenius, Revista Ciencia y Tecnología is the property of Universidad Politecnica Salesiana 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 merging of a falling drop with a water surface gives rise to a series of hydrodynamic phenomena that differ in time and space scales. Among them, fast unsteady flows are distinguished, in the process of which deformed underwater caverns and gas cavities separated from them are formed. When the surface of the separating gas cavity closes, the formed bubble undergoes volumetric oscillations, which, in turn, generate short acoustic packets propagating under water and in the air. Experimental data are presented in which the sequence of the formation of caverns is traced, and the processes of the formation and detachment of bubbles and accompanying acoustic signals are identified and detailed. In the composition of the sound packets recorded in the water and air environments, there are differences associated with the characteristics of propagation (transient damping at the water-air boundary) and the influence of the transmission functions of the hydrophone and microphone. In the case of detachment, reattachment, and reseparation of an air bubble from successive caverns, the frequency of the emitted signal increases. Despite the highly irregular shape of the emitting bubbles, the emission frequency remains constant, which indicates the volume of the bubble as the governing parameter of acoustic emission. [ABSTRACT FROM AUTHOR]

Particle Image Velocimetry (PIV) is used to study the nonstationary flow pattern around a drop of a dielectric liquid of dibutyl phthalate surrounding water of weak conductivity under the action of a microsecond current pulse. It has been found that the time of existence of the induced vortex flow in water significantly exceeds the duration of the current pulse. During the action of the pulse, only small perturbations develop on the surface of the drop, while the final perturbations of the surface develop at much longer times, exceeding the duration of the current pulse by two or more orders of magnitude, and are associated with the evolution of the water flow around the drop. It is shown that the value of the maximum velocity in the induced water flow is affected by the potential of the needle at a constant duration and amplitude of the current. [ABSTRACT FROM AUTHOR]

South Korea is one of the leading markets for the e-commerce industry. In line with the rapid growth of the e-commerce industry, the parcel delivery volume in Korea has also proliferated. Despite the developments in the Korean e-commerce and courier industries, consumers still experience a high package damage rate. In response, many packaging engineers in Korea have raised the need for new parcel shipping environment tests that reflect the Korean ground shipping environment in order to properly optimize packages. However, only limited information on the Korean parcel shipping environment is currently available. Therefore, this study focused on measuring and analyzing the shock and drop levels that parcels experience during ground shipping in Korea. Shock data were collected from a total of sixty one-way shipments for small, lightweight packages and medium, mid-weight packages. The findings revealed that the two types of boxes do not experience significantly different numbers of shock events or drop heights in the Korean parcel delivery environment. Furthermore, the number of shock events that occur in Korea is substantially less than the international testing standard and less than in previous studies conducted in both Europe and the USA. In contrast, however, the drop heights are higher than those in the international testing standard and previous studies. Shock events were found to occur most frequently on the edges and to be concentrated around the bottoms of the packages. Most shock events happen while packages are loaded and unloaded at hub terminals and sub terminals.

En la actualidad la práctica del ciclismo ha tenido un incremento considerable, así como el uso de bicicletas de montaña (Mountain Bike, MTB, en inglés), de cuadro rígido, utilizadas como medio de transporte y para competencia, debido a su costo asequible. Este tipo de bicicletas, al ser utilizadas para varios propósitos, presentan esfuerzos variados en su cuadro, que conllevan a sobrepasar las exigencias de diseño, presentándose fallos en las vainas superiores. Este tipo de fallo es analizado en este estudio, motivo por el cual se levanta la información referente al material del cuadro, cargas actuantes y modelado 3D. Posterior se genera un análisis de homologación del fallo y se determina una propuesta de mejora aplicando optimización geométrica, donde se determina un espesor de 3,50 mm en las vainas superiores, garantizando la resistencia del cuadro de bicicleta bajo las condiciones de estudio; es decir, un drop de 60 cm y carga de 74 kg, con la cual se garantiza que el esfuerzo en las vainas superiores no sobrepase el esfuerzo último del material de 890,94 MPa.

The transverse impact of a pulsed water microjet on individual cylindrical fibers is studied. The stages of ejection, breakup, and collision of the microjet were recorded by high-speed photography. A significant deceleration of the microjet by the fiber and its splitting into two parts were revealed. The mechanisms of the observed phenomena and the influence of various factors are discussed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The processes of interaction of liquid droplets with solid surfaces have become of interest to many researchers. The achievements of world science should be used for the development of technologies for spray cooling, metal hardening, inkjet printing, anti-icing surfaces, fire extinguishing, fuel spraying, etc. Collisions of drops with surfaces significantly affect the conditions and characteristics of heat transfer. One of the main areas of research into the interaction of drops with solid surfaces is the modification of the latter. Changes in the hydrophilic and hydrophobic properties of surfaces give the materials various functional properties—increased heat transfer, resistance to corrosion and biofouling, anti-icing, etc. This review paper describes methods for obtaining hydrophilic and hydrophobic surfaces. The features of the interaction of liquid droplets with such surfaces are considered. The existing and possible applications of modified surfaces are discussed, as well as topical areas of research. [ABSTRACT FROM AUTHOR]

When a water drop is placed on a hot solid surface, it either undergoes explosive contact boiling or exhibits a stable state. In the latter case, the drop floats over an insulating layer of vapor generated by rapid vaporization of water at the surface/drop interface; this is known as the Leidenfrost state. Here, we discuss a previously unrecognized steady state in which a water drop "stands" on a hot smooth surface. In this state, the drop stabilizes itself with partial adhesion on the hot surface, leading to unique deformation and rotation behavior reminiscent of Sufi whirling--a form of spinning dance. Our analysis of this standing Leidenfrost state reveals the underlying mechanisms that drive the drop's stable partial adhesion and subsequent deformation with rotation. The heat-transfer efficiency of this standing state is up to 390% greater than that of the traditional floating Leidenfrost state. [ABSTRACT FROM AUTHOR]

The processes of freezing of water droplets sitting on a substrate after exposure to nanosecond spark discharges have been experimentally studied. It has been found that the droplets subjected to spark discharge treatment freeze much earlier than those unexposed to discharges. The analogy of the observed processes with the well-known Mpemba effect is noted. A qualitative explanation is given for the observed effect: rapid freezing is due to hydrated electrons, which are formed upon contact of water with plasma and play the role of crystallization centers. [ABSTRACT FROM AUTHOR]

The relevance. The development of fundamentally new strategies and technical solutions leading to an increase in energy efficiency and resource saving of cooling systems for energy-saturated equipment is impossible without the creation of new structural materials with targeted functional properties. Promising cooling systems of heat-loaded equipment, for example, 5G communication devices emitting high-density heat fluxes (up to 1000 W/cm2), include systems based on drip irrigation. Such cooling makes it possible to increase the intensity and uniformity of heat removal, and significantly reduce the coolant consumption. However, the results obtained so far show that the use of traditional approaches (the use of surfaces made of steel, copper, aluminum and their alloys, processed by grinding or polishing) does not allow solving the problem of intensive cooling of surfaces that release high-density heat fluxes. Laser strategies for processing heat transfer surfaces are one of the most effective ways to intensify evaporation and boiling. In relation to the development of laser systems in the last decade, financially sound technologies for creating targeted, functional surface properties of metals have become available. The practical use of laser-modified heat-transfer surfaces of cooling systems can solve a number of problems associated with meeting the growing global demand for energy resources, in particular, when intensifying the removal of high-density heat fluxes from elements of energy-saturated equipment by shifting the heat transfer crisis of the 2nd kind to higher temperatures. The purpose is to assess the possibility of shifting the heat transfer crisis (Leidenfrost effect) to higher temperatures by modifying heat transfer heating surfaces with nanosecond laser radiation. Methods. Using nanosecond laser processing, unique textures with specified geometric characteristics were created on typical materials used in practice in the design of heat transfer surfaces for heating cooling systems. Texture characteristics were determined using confocal and electron microscopy equipment. The Leidenfrost effect was recorded using a specially made setup with equipment for the shadow optical method and high-speed video recording of fast physical processes. Results. The modes of a single nanosecond laser pulse action on the stainless steel and aluminum surfaces were detected. These modes guarantee the formation of an ablation crater. We showed the possibility to apply the graphic-analytical technique for the formation of a given microtexture during the treatment of metal surfaces with nanosecond laser radiation. Laser treatment of metal surfaces with pulse energy up to 0,6 mJ makes it possible to control the boiling crisis characteristics (2nd kind), in particular, the Leidenfrost temperature, over a wide range of values by more than 110 °C on aluminum surface and by more than 45 °C on stainless steel surface in atmospheric conditions when using distilled deaerated water as a heat carrier due to the formed texture and superhydrophilic properties.

This work discusses the kinetics of the separation process of a solution consisting of vegetable oil and a low-boiling hydrocarbon solvent in a distillation process. The efficiency of the distiller is affected by capital costs, energy costs, and quality characteristics of the resulting oil. The mass transfer rate depends on the nature of the phase equilibrium, mass transfer coefficient, and contact area between the phases. The issues of mathematical modeling of heat and substance exchange processes going in the spraying zone of the final distillation device of vegetable oil are presented. The influence of various factors such as initial temperature and concentration of the feed liquid, vacuum pressure, and particle diameter on the distillation process is also discussed. The process of scattering liquid in a channel sprayer is given to two zones A and B, that is, mathematical and computer models of the processes of heat and substance exchange, which are carried out by turning the liquid into a drop, and the results of the computer model are analysed.

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Copyright of Ordnance Industry Automation is the property of Editorial Board for Ordnance Industry Automation 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.)

Hyperlipidemia is the elevated concentration of lipids in the blood, and it increases the probability of arterial obstruction, infarctions, and other complications of the circulatory system. While there are indications that qualitative analysis of blood stains could potentially identify patients with this pathology, the efficacy of this method remains uncertain. In this paper, we report an experimental study that investigates the formation of patterns in dried blood droplets with varying concentrations of ultrapure water. Two blood samples, one healthy and one with moderate hyperlipidemia, were examined to determine the ideal water and blood mixtures for detecting high lipid concentrations. Numerous intricate patterns were observed throughout the central region and periphery of the dried droplet. These patterns encompass various forms, such as plaques, bump-like patterns, and a range of cracks including random, radial, and ortho-radial configurations. By calculating the entropy of the Gray Level Co-occurrence Matrix (GLCM) and analyzing ROC curves, we determined that solutions with 4% and 12% hematocrit (indicating a high percentage of ultrapure water) exhibit over 95% accuracy in differentiating high lipid concentrations. These findings provide a promising outlook for the development of diagnostic methods based on the study of diluted blood coatings. [ABSTRACT FROM AUTHOR]

[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]