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In this study, a new criterion for the splashing of a droplet on a dry smooth surface is established from high-fidelity numerical simulations. The new criterion involves the Weber number, Reynolds number and contact angle. A new splashing mode, termed spreading splashing, is proposed, which predominates for contact angles below 120 degrees. For contact angles above 120 degrees, prompt splashing dominates. For contact angles above 90 degrees, there exists a critical Weber number of around 60, below which splashing does not occur. [ABSTRACT FROM AUTHOR]

The impact of liquid droplets on the ultracold surface affects significantly the cold start performance of internal combustion engines but the splash and spreading characteristics after impacting on the ultracold surface are not clearly understood. Therefore, droplets with various physical parameters impacting on the Al–Si alloy surface have been selected for the study under various surface temperatures (–40°C ≤ ≤ 25°C) and droplet impact velocities (0.96 m/s ≤ ≤ 3.52 m/s). The ultracold surface ( = –40°C) is beneficial for corona splash, and droplets with the higher Oh number impacting on the ultracold surface easily produce corona splash as the main splash pattern. The ultracold surface assisted in enhancing the stability of the levitated lamella formation, and avoided the effects of rough surfaces, so the upper splash criterion is established to predict the transition from spreading to splash. The decreasing surface temperature reduces the maximum spreading diameter () of low solidification point droplets (ethanol, n-propanol, and winter diesel). Based on the assumptions of qualitative temperature, the empirical correlation of the is created for the Ts from 25 to –40°C. [ABSTRACT FROM AUTHOR]

An analytical model for droplet impact onto a porous substrate is presented, based on Wagner theory. An idealised substrate boundary condition is introduced, mimicking the effect of fluid entry into a genuinely porous substrate. The asymptotic analysis yields a solution for a small porous correction with free-surfaces and pressures compared with the impermeable case. On a global scale, it is found that the impact region on the substrate grows more slowly with porosity included due to loss of mass into the substrate. The spatial distribution of liquid volume flux into the substrate is also described. Locally near the turn-over regions, the expected jetting along the surface is calculated with the same volume flux but the jet is found to be slower and thicker than for an impermeable substrate. [ABSTRACT FROM AUTHOR]

A transient 3D mathematical model is developed to study the surging auxiliary slag skimming process in molten iron ladle. A new mathematical model using the large eddy simulation is built for the gas–metal–slag three‐phase flow in the ladle. The Eulerian volume of fluid model is used for tracking the liquid–slag–air free surfaces, and the Lagrangian discrete phase model is used for describing the bubble movement. The procedure of bubble coming out of the liquid and getting into the air is modeled using a user‐defined function. The results show that optimizing the distance of the lance L and the injection volume Q can better the shape of the slag eye, increase the curvature radius of the slag eye on the side of the iron mouth, and broaden the area of the slag eye. At the same time, it can also improve the fluctuation of the slag layer and the liquid surface of molten iron, and reduce the splashing of molten iron and slag entrapment phenomenon, thus improving the slag skimming efficiency. [ABSTRACT FROM AUTHOR]

In this study, a new criterion for the splashing of a droplet on a dry smooth surface is established from high-fidelity numerical simulations. The new criterion involves the Weber number, Reynolds number and contact angle. A new splashing mode, termed spreading splashing, is proposed, which predominates for contact angles below 120 degrees. For contact angles above 120 degrees, prompt splashing dominates. For contact angles above 90 degrees, there exists a critical Weber number of around 60, below which splashing does not occur.

Spray impacts can be found in several technical applications and consist of many single droplets, which impact under different trajectories on wetted walls. This study investigates the asymmetric crown morphology resulting from an oblique impact ( α = 60°) of a single droplet on a horizontal and quiescent wall film of the same liquid. A droplet generator with an accelerated needle releases the droplets ( D = 1.5 mm) in a controlled trajectory on a thin film ( h f / D = 0.2). The impact process is recorded from two perspectives with two synchronized high-speed cameras. Varying the Weber number within the splashing regime reveals distinct crown morphologies, which are described in detail. For W e < 500, a single central finger develops at the front of the crown, with subsequent detachments of secondary droplets. At higher W e (>500), a collision of the crown with the wall film shortly after impact introduces disturbances into the rim, leading to two fingers in the middle of the front crown. A further increase in W e (>600) intensifies the crown–film interaction, resulting in an early ejection of tiny droplets and a complete breakup of the front rim. The influence of W e on the crown morphology during an oblique impact is also compared to the normal impact (90°). This study paves the way for a classification of impact regimes and a comprehensive picture of the oblique impact process, which deserve more investigation. [ABSTRACT FROM AUTHOR]

In recent years, forest fires and maritime accidents have occurred frequently, which have had a bad impact on human production and life. Thus, the development of seaplanes is an increasingly urgent demand. It is important to study the taxiing process of seaplanes for the development of seaplanes, which is a strong nonlinear fluid-structure interaction problem. In this paper, the Smoothed Particle Hydrodynamics (SPH) method based on the Lagrangian framework is utilized to simulate the taxiing process of seaplanes, and the SPH results are compared with those of the Finite Volume Method (FVM) based on the Eulerian method. The results show that the SPH method can not only give the same accuracy as the FVM but also have a strong ability to capture the splashing waves in the taxiing process, which is quite meaningful for the subsequent study of the effect of a splash on other parts of the seaplane.

Critical Weber numbers (Wecr) for droplet splashing are investigated by considering the geometrical morphologies of hydrophobic micro/nano-textured surfaces and the viscosity of lubricants. A decreasing trend of Wecr with respect to pillar spacing is evident for all textured and lubricant-infused surfaces (LISs), but it is independent of the pillar diameter effect. Additionally, the overall Wecr of the LIS exceeded that of the micro/nano-textured surfaces. The results show that the early droplet splash on micro/nano-textures may be attributed to the slip condition, decreasing the friction loss of airflow and increasing Uair/U0 and K-H instability. Moreover, the slip velocity on the LISs decreases as the lubricant viscosity increases in the order uslip (101) > uslip(105) > uslip(107). Therefore, an increase in slip velocity facilitates earlier droplet splashing on low-viscosity LIS101 than on high-viscosity LIS105 and LIS107. Furthermore, the droplet retraction behavior beyond the maximum spreading varied significantly based on the surface wetting characteristics. [ABSTRACT FROM AUTHOR]

[Display omitted] Droplet impact onto liquid pools is a canonical scenario relevant to numerous natural phenomena and industrial processes. However, despite their ubiquity, multi-fluid systems with the drop and pool consisting of different liquids are far less well understood. Our hypothesis is that the post-impact dynamics greatly depends on the pool-to-droplet viscosity ratio μ p / μ d , which we explore over a range of six orders of magnitude using a combination of experiments and theoretical approaches (mathematical modelling and direct numerical simulation). Our findings indicate that in this scenario the splashing threshold and the composition of the ejecta sheet are controlled by the viscosity ratio. We uncover that increasing the pool viscosity decreases the splashing threshold for high viscosity pools ( μ p / μ d ≳ 35) when the splash comes from the droplet. By contrast, for low viscosity pools, the splash sheet comes from the pool and increasing the pool viscosity increases the splashing threshold. Surprisingly, there are conditions for which no splashing is observed under the conditions attainable in our laboratory. Furthermore, considering the interface velocity together with asymptotic arguments underlying the generation of the ejecta has allowed us to understand meaningful variations in the pressure during impact and rationalise the observed changes in the splashing threshold. [ABSTRACT FROM AUTHOR]

The impingement of a short-duration water jet on a pool of molten Rose's metal is studied experimentally herein. Short-duration water jet impacting on the free surface of a molten metal pool with a temperature of 300 °C are generated with a pneumatic water delivery system, with two-camera high-speed video registration. A total of 14 experimental series, each containing 5 repeated tests, are performed for a water volume of 0.2–1 mL and a jet impact velocity of 4.1–9.0 m/s. The cavity development in the melt layer is studied, with the main stages described herein. Despite the significantly higher density of melt in comparison with water, the cavity can reach the melt pool bottom; furthermore, its further collapse results in the formation of a central jet rising to the height of a few centimeters. The maximum height of the central jet is shown to depend linearly on the total momentum of the water jet, and a semi-logarithmic correlation is found for the maximum diameter of the cavity. Repeatability analysis is performed within each experimental series, and the relative standard deviation for the melt splash height is shown to be from 8.8% to 26.8%. The effects of the pool depth, the vessel shape, and the water temperature are weaker in the range of the experimental parameters used here. [ABSTRACT FROM AUTHOR]

[Display omitted] Needle-free injections using microfluidic jets could be optimized by reducing splashing and controlling injection depth. However, this is impeded by an incomplete understanding on how jet characteristics influence impact outcome. We hypothesise that exploring the relation between microfluidic jet characteristics and substrate shear modulus on impact behavior will assist in predicting and giving insights on the impact outcome on skin and injection endpoints. To do so, a setup using microfluidic chips, at varying laser powers and stand-off distances, was used to create thermocavitation generated microfluidic jets with ranging characteristics (velocity: 7–77 m/s, diameter: 35–120 μm, Weber-number: 40–4000), which were impacted on substrates with different shear modulus. Seven impact regimes were found, depending on jet Weber-number and substrate shear modulus, and we identified three thresholds: i) spreading/splashing threshold, ii) dimple formation threshold, and iii) plastic/elastic deformation threshold. The regimes show similarity to skin impact, although the opacity of skin complicated determining the threshold values. Additionally, we found that jet velocity has a higher predictive value for injection depth compared to the Weber-number, and consequently, the jet-diameter. Our findings provide fundamental knowledge on the interaction between microfluidic jets and substrates, and are relevant for optimizing needle-free injections. [ABSTRACT FROM AUTHOR]

This paper presents the morphological evolution characteristics of a droplet impacting a V-shaped wall by using the lattice Boltzmann method (LBM). Four parameters are investigated comprehensively. The parameters vary over wide ranges: surface wettability ( 60 ∘ ≤ θ eq ≤ 120 ∘ ), Weber number ( 102.27 ≤ We ≤ 3681.82 ), bending angle of the V-shaped wall (90 ∘ ≤ θ ≤ 180 ∘ ), and eccentricity ratio (0 ≤ b ≤ 0.5). Two types of collision are observed: deposition and breakage. For breakage, the number of satellite droplets increases against the increment of We. The splashing occurs for a high We. And the lamella ejection is observed on the hydrophilic wall and the neutral wall. The lamella ejection will be slight against the increase of θ eq , while it will become obvious against the increment of θ . In addition, the nondimensional spreading length, width, and height are measured and analyzed. Regime maps are established based on We, Re, and θ . [ABSTRACT FROM AUTHOR]

Droplet ejections from a molten tungsten electrode during alternating current tungsten inert gas (AC TIG) welding were observed successfully by a high-speed video captured at 75,000 fps. The welding conditions and timings that were likely to occur were investigated. The electrode surface temperature was also measured. A crater was formed on the surface of the electrode, and a droplet ejection occurred following the separation of the tip of the ridge growing from the centre of the crater. A series of droplet ejections occurred on a time scale of approximately 0.4 ms. Our results showed that the high temperature of the electrode surface was the common factor for droplet ejections. The dominant force for droplet ejection was discussed by estimating the balance of forces acting on the molten electrode surface. The pressure due to surface tension was the largest pressure at any time during the AC cycle, which decreased in the second half of the EP period. Our findings suggest that the surface tension was the dominant force for changing the electrode shape and that droplet ejections occurred when the surface tension decreased due to the increase in the electrode surface temperature. [ABSTRACT FROM AUTHOR]

Background: Water is a product taken for granted and assumed to be a safe commodity in intensive care units (ICU). Biofilm readily becomes established in complex water services presenting a risk to vulnerable patients. Harboured within biofilms are opportunistic pathogens which can be transmitted via hand contact, splashing, aerosol and indirect contact through medical equipment. Evidence linking the role of water services in transmission of infection to patients in ICUs has increased in recent years. Aims: This research based commentary set out to identify current problems with water and wastewater systems in ICU settings. Methods: Databases and open source information was used to obtain data on current water and wastewater-related issues in ICU settings. This and the authors experiences have been used to describe current challenges. Findings: the authors found a number of problems with water systems in ICU to which there has not been a cohesive response in terms of guidance to support users and designers. The resultant void permits new projects to proceed with suboptimal and designs which place patients and staff at risk. Discussion: Hand hygiene stations are frequently misused or close enough to patients such that splashing poses a transmission risk. The wastewater system (drain) also presents a risk, from where Gram-negative antibiotic resistant organisms may be dispersed resulting in untreatable patient infections. The water and wastewater system provide a superhighway for the movement of pathogenic microorganisms and these risks need to be addressed if we are to safeguard vulnerable users in ICU. [ABSTRACT FROM AUTHOR]

Background: Evidence linking the role of water services in transmission of infection to patients in ICUs has increased in recent years. Aims: This research based commentary set out to identify potential solutions for water and wastewater systems in ICU settings. Methods: Databases and open source information was used to obtain data on approaches to water and wastewater-related issues in ICU settings. This and the authors experiences have been used to describe approaches to these problems. Findings: The lack of updated guidance has required some ICUs to develop unique responses, including 'water free' patient care combined with reduction in water services. The options consider guidance, compliance, training and education as key factors to successful outcomes and protecting vulnerable patients in ICU. Discussion: The authors found a number of problems with water and wastewater systems in ICU to which there has not been a cohesive response in terms of guidance to support users and designers. The resultant void permits new projects to proceed with suboptimal and designs which place patients and staff at risk. As an interim measure a series of solutions suitable for existing units and new builds need to be considered. [ABSTRACT FROM AUTHOR]

Metal droplet deposition is of fundamental importance in many industrial and manufacturing processes. An in‐depth understanding of the fundamental issues of metal droplet deposition is particularly crucial for developing droplet deposition‐based engineering manufacturing technologies. This review systematically introduces the evolution of metal droplet deposition stages and characteristic behaviors in terms of metal droplet deposition dynamics. The characteristic morphologies of single‐metal droplets after solidification, that is, gas entrapment, ripples, bulging edges, and splashing, are reviewed. The formation mechanisms and influencing factors of different droplet morphologies are summarized. Moreover, the deposition strategy of multiple metal droplets to promote good interfacial bonding is further concluded. Based on these theoretical foundations, three typical engineering manufacturing techniques based on metal droplet deposition, that is, thermal spraying, soldering, and droplet‐based 3D printing, are presented to elucidate further the advantages and potential of metal droplet deposition applied to engineering manufacturing. Finally, some existing problems and future research perspectives are discussed. [ABSTRACT FROM AUTHOR]

The dynamics of transient liquid beryllium flows induced on the ITER first wall during the current quench stage of unmitigated vertical displacement events are modelled by means of two-dimensional Navier–Stokes simulations. The study focuses on melt that is driven to the first wall panels' chamfered edges, where free-surface instabilities are the most likely to be seeded. Beyond their impact on plasma-facing component damage, these instabilities potentially result in material ejection in the form of droplets, which may ultimately solidify into dust and accumulate in the vessel. Based on prior integrated numerical predictions of quenching magnetic equilibria, wall energy deposition and melt-related damage in a concrete worst-case disruption scenario, the simulations suggest that, although the liquid layer is significantly destabilized, only 5% of the total melt mass created on the wall surface is lost through ejection. This result can serve as a basis to refine the estimates of the real transient-induced beryllium dust inventory expected in ITER. [ABSTRACT FROM AUTHOR]

Background: Since the outbreak of the SARS-CoV-2 virus in December 2019, the COVID-19 pandemic continues to threaten global stability. Transmission of SARS-CoV-2 is mostly by respiratory droplets and direct contact but viral RNA fragments have also been detected in the faecal waste of patients with COVID-19. Cleanliness and effective sanitation of public toilets is a concern, as flushing the toilet is potentially an aerosol generating procedure. When the toilets are of the squatting type and without a cover, there exists a risk of viral contamination through the splashing of toilet water and aerosol generation. Objective: This study aims to determine whether the cleanliness of public toilets was a concern to the general population during the COVID-19 pandemic, and whether a squatting toilet was preferred to a seated design. Methods: A questionnaire was designed and posted on “WeChat” contact groups of the investigators. Results: The survey showed that 91% of participants preferred squatting toilets, but that 72% were apprehensive of personal contamination when using public toilets. Over 63% of the respondents had encountered an incidence of water splash and would prefer public toilets to be covered during flushing and 83% of these respondents preferred a foot-controlled device. Conclusion: This survey suggests that consideration should be given to the installation of a simple foot-controlled device to cover public squatting toilets to help restrict potential COVID-19 contamination and to meet hygienic expectations of the public.

Abstract This work investigates the splashing behaviors of droplets impacting on solid surfaces and mainly focuses on the characteristics of secondary droplets. According to the experimental results, two different splashing patterns, corona splash and levitating-lamella breakup, are observed. A new breakup mode, named rim-segmenting, is found during the levitating-lamella breakup. In particular, the detailed information of the splashing secondary droplets, including the size, velocity, angle, and total volume of the splashing secondary droplets is obtained from the experimental data. The size distribution of the splashing secondary droplets obeys the gamma distribution function. The average diameter and splashing angle of the secondary droplets are mainly related to the Reynolds number Re, and can be expressed as functions of Re. High impact velocity and liquid viscosity will result in a wider size distribution range of splashing secondary droplets. We also put forward an empirical model to predict the total splashing volume, which is consistent with the experimental data both in this work and previous studies. This work is believed to provide insights on the prediction of the characteristics of splashing secondary droplets.

A recently developed conservative level set model, coupled with the Navier-Stokes equations, was invoked to simulate non-spherical droplet impact in three dimensions. The advection term in the conservative level set model was tackled using the traditional central difference scheme on a half-staggered grid. The pressure velocity coupling was decoupled using the projection method. The inhouse code was written in Fortran and was run with the aid of the shared memory parallelism, OpenMP. Before conducting extensive simulations, the model was tested on meshes of varied resolutions and validated against experimental works, with satisfyingly qualitative and quantitative agreement obtained. The model was then employed to predict the impact and splashing dynamics of non-spherical droplets, with the focus on the effect of the aspect ratio. An empirical correlation of the maximum spread factor was proposed. Besides, the number of satellite droplets when splashing occurs was in reasonable agreement with a theoretical model. [ABSTRACT FROM AUTHOR]

[Display omitted] Droplets impacting dry solid substrates often splash above a certain threshold impact velocity. We hypothesise that substrate curvature alters splashing thresholds due to a modification to the lift force acting on the lamella at the point of breakup. We have undertaken high-speed imaging experiments of millimetric droplets impacting convex and concave surfaces to establish splashing thresholds and dynamics across a wide range of substrate geometries and impact conditions. Our findings indicate that the tendency of droplets to splash is proportional to the reciprocal of the substrate's radius of curvature, independent of whether the substrate is convex or concave, with it being harder for droplets to splash on small spheres. Moreover, we consistently parameterise the axisymmetric splashing threshold across all curved substrate geometries via a modification to the well-known splashing ratio. Finally, the splashing dynamics resulting from initial asymmetry between the impacting droplet and curved substrate are also elucidated. [ABSTRACT FROM AUTHOR]

Laser scabbling is one of the options that can be used for removal of contaminated concrete when decommissioning and dismantling of nuclear power plant. Laser scabbling can be advantageous for such purpose because laser can transmit through long-distance and the system operates remotely in dry condition while minimizing the human access to the radioactively contaminated area. In order to investigate the applicability of laser scabbling on concrete, the experimental program was conducted on concrete with various moisture content, fine aggregate ratio with different paste content. According to the results, concrete in oven dry condition showed no efficiency on laser scabbling. The surface of the concrete was vitrified as a result. However, a 5 kW fiber laser with 900 mm stand-off distance was successfully applied for laser scabbling of air dry and saturated surface dry concretes. It was found that the moisture is a prerequisite requirement for successful laser scabbling of concrete. The changes in fine aggregate ratio and paste content did not affect the efficiency of laser scabbling.

The impingement of a short-duration water jet on a pool of molten Rose’s metal is studied experimentally herein. Short-duration water jet impacting on the free surface of a molten metal pool with a temperature of 300 °C are generated with a pneumatic water delivery system, with two-camera high-speed video registration. A total of 14 experimental series, each containing 5 repeated tests, are performed for a water volume of 0.2–1 mL and a jet impact velocity of 4.1–9.0 m/s. The cavity development in the melt layer is studied, with the main stages described herein. Despite the significantly higher density of melt in comparison with water, the cavity can reach the melt pool bottom; furthermore, its further collapse results in the formation of a central jet rising to the height of a few centimeters. The maximum height of the central jet is shown to depend linearly on the total momentum of the water jet, and a semi-logarithmic correlation is found for the maximum diameter of the cavity. Repeatability analysis is performed within each experimental series, and the relative standard deviation for the melt splash height is shown to be from 8.8% to 26.8%. The effects of the pool depth, the vessel shape, and the water temperature are weaker in the range of the experimental parameters used here.

Droplet ejections from a molten tungsten electrode during alternating current tungsten inert gas (AC TIG) welding were observed successfully by a high-speed video captured at 75,000 fps. The welding conditions and timings that were likely to occur were investigated. The electrode surface temperature was also measured. A crater was formed on the surface of the electrode, and a droplet ejection occurred following the separation of the tip of the ridge growing from the centre of the crater. A series of droplet ejections occurred on a time scale of approximately 0.4 ms. Our results showed that the high temperature of the electrode surface was the common factor for droplet ejections. The dominant force for droplet ejection was discussed by estimating the balance of forces acting on the molten electrode surface. The pressure due to surface tension was the largest pressure at any time during the AC cycle, which decreased in the second half of the EP period. Our findings suggest that the surface tension was the dominant force for changing the electrode shape and that droplet ejections occurred when the surface tension decreased due to the increase in the electrode surface temperature.

This paper studies the interaction of two droplets splashing on a stationary film. A source term is included in the large-density-ratio pseudopotential lattice Boltzmann method to achieve tuneable surface tension. This model offers excellent numerical accuracy and stability for droplet impacts on liquid films. The influence of the Reynolds number, Weber number, film thickness, and horizontal/vertical distance between the droplets on the crown geometry evolution is investigated. The energy loss during the impact process and the velocity discontinuity in the liquid film are the two key factors affecting the stability and evolution process of the crown. A smaller Reynolds number or thicker liquid film enhances the energy loss and decreases the velocity discontinuity, leading to more stable side and central jets. An increase in the horizontal distance between the droplets reduces the velocity discontinuity, causing the central jet height to decrease. An increase in the Weber number does not affect the energy loss or velocity discontinuity, but the lower surface tension leads to a dramatic deformation in both the central and side jets. A vertical distance between the two droplets causes an asymmetrical evolution of the crown geometry, and postpones the breakup time of the central jet .

Electrospinning provides a versatile, efficient and low-cost method for the preparation of continuous nanofibres from various polymers. In this study, the polyhedral oligomeric silsesquioxanes (POSS) block copolymer was synthesized via atom transfer radical polymerization. The smooth fiber, porous fiber or hierarchically porous microspheres were prepared by electrospinning from POSS block copolymer, poly(vinylidene fluoride) (PVDF) and aluminium oxide (Al2O3). The influence of copolymer concentration, the ratio of the solvents, the diameter and concentration of the Al2O3 on the surface morphology were investigated. Porous fibers and porous microspheres were prepared by regulating the ratio of the solvents from the phase separation and breath figure methods. The dynamic behavior of the water droplet with the constant volume impacting on the electrospinning films were reported. The morphology evolution, restitution coefficient, the change of energy of the water droplets are examined. The droplet bounces several times on the superhydrophobic surface, while the droplet remains pinned and does not rebound when the contact angles was lower than 150°. On the other hand, the water droplets were splashed on the Al2O3 based electrospinning films. Finally, the mechanical properties of the electrospinning films were investigated.

Inappropriate slag foaming is the main cause of splashing in basic oxygen furnace (BOF). Through the physical modeling, the effects of slag–metal reaction rate, viscosity of slag, slag–metal interface tension, and lance height on the slag foaming are investigated, and further analyzed the relation between the extent of BOF slag foaming and splashing. Consequently, two patterns of overflowing splashing and eruptive splashing and their critical conditions are summarized. The experimental results indicate that gas released by slag–metal reaction is primarily responsible for slag foaming in BOF, and the maximum height of foamed slag increases with increasing reaction rate of slag–metal. Moreover, an increase in dynamic viscosity of slag prevents the foam structure transforming from spherical foam to polyhedral foam, and thus improves the maximum foaming ability of slag and the stability of foam structure. With decreasing slag–metal interface tension, the slag–metal emulsification and the stability of foam structure are promoted. Finally, it is concluded that overflowing splashing occurs under the conditions of the higher dynamic viscosity of slag and the larger gas generation amount; whereas, eruptive splashing occurs under the conditions of the lower dynamic viscosity of slag and the higher gas generation rate. [ABSTRACT FROM AUTHOR]

The study was carried out to design and develop an ozonation treatment system for the sanitization of fresh produce before storage. The developed system was evaluated for minimally processed onions based on the kinetics of degradation, application methods, homogeneity of dissolution, and specific energy consumption. The sanitization process was then optimized for cut onion slices using a Box-Behnken design under Response Surface Methodology to study the effects of ozone concentration (1–5 ppm), exposure time (3–8 min), and aqueous pH (3–5) on microbial log reductions, pyruvate content, color change, and overall acceptability. The results obtained showed that degradation kinetics of dissolved ozone followed a first-order reaction with a half-life of 18.23 min. Among the different methods of ozone application tested at 5 ppm ozone concentration, the splashing method yielded the highest microbial log reductions (5.04) followed by dipping (4.5) and spraying (4.22) methods. For the sanitization of cut slices of onion, it was observed that aqueous ozone at 5 ppm concentration splashed on the surfaces for 8 min and an aqueous pH of 3.01 yielded optimized sanitization, whereas microbial log reductions, pyruvate content, and overall acceptability were recorded as 5.6 log reductions, 0.127 µM/mL, and 8.2, respectively. Overall, the system was found to be effective for the sanitization of minimally processed onions. [ABSTRACT FROM AUTHOR]

This work investigates the splashing behaviors of droplets impacting on solid surfaces and mainly focuses on the characteristics of secondary droplets. According to the experimental results, two different splashing patterns, corona splash and levitating-lamella breakup, are observed. A new breakup mode, named rim-segmenting, is found during the levitating-lamella breakup. In particular, the detailed information of the splashing secondary droplets, including the size, velocity, angle, and total volume of the splashing secondary droplets is obtained from the experimental data. The size distribution of the splashing secondary droplets obeys the gamma distribution function. The average diameter and splashing angle of the secondary droplets are mainly related to the Reynolds number Re, and can be expressed as functions of Re. High impact velocity and liquid viscosity will result in a wider size distribution range of splashing secondary droplets. We also put forward an empirical model to predict the total splashing volume, which is consistent with the experimental data both in this work and previous studies. This work is believed to provide insights on the prediction of the characteristics of splashing secondary droplets. [ABSTRACT FROM AUTHOR]

This paper studies the interaction of two droplets splashing on a stationary film. A source term is included in the large-density-ratio pseudopotential lattice Boltzmann method to achieve tuneable surface tension. This model offers excellent numerical accuracy and stability for droplet impacts on liquid films. The influence of the Reynolds number, Weber number, film thickness, and horizontal/vertical distance between the droplets on the crown geometry evolution is investigated. The energy loss during the impact process and the velocity discontinuity in the liquid film are the two key factors affecting the stability and evolution process of the crown. A smaller Reynolds number or thicker liquid film enhances the energy loss and decreases the velocity discontinuity, leading to more stable side and central jets. An increase in the horizontal distance between the droplets reduces the velocity discontinuity, causing the central jet height to decrease. An increase in the Weber number does not affect the energy loss or velocity discontinuity, but the lower surface tension leads to a dramatic deformation in both the central and side jets. A vertical distance between the two droplets causes an asymmetrical evolution of the crown geometry, and postpones the breakup time of the central jet. [ABSTRACT FROM AUTHOR]

Free surface lubrication of rotating cylinders by Newtonian liquid jets was investigated at different impingement positions, jet‐ and circumferential velocities. The interaction between impinging round laminar jet and rotating surface was characterised by high‐speed imaging. Compared to flat surface impingement, the liquid deposition mechanism is more complex and often accompanied by phenomena such as splashing, jet deflection and formation of radial surface stripes. Liquid splashing initially develops in direct deposition regime due to hydraulic jump‐induced droplet shedding, transitioning to lamella instability splash at higher Reynolds numbers. The critical Reynolds number for splash onset is of same order of magnitude as for flat surface impingement and fairly constant at low relative jet impingement angles, but increases exponentially when angle approaches 90°. Liquid film width and thickness were both determined proportional to the square root of the jet/surface velocity ratio, with respective power law models in good agreement with measured values. [ABSTRACT FROM AUTHOR]

Electrospinning provides a versatile, efficient and low-cost method for the preparation of continuous nanofibres from various polymers. In this study, the polyhedral oligomeric silsesquioxanes (POSS) block copolymer was synthesized via atom transfer radical polymerization. The smooth fiber, porous fiber or hierarchically porous microspheres were prepared by electrospinning from POSS block copolymer, poly(vinylidene fluoride) (PVDF) and aluminium oxide (Al2O3). The influence of copolymer concentration, the ratio of the solvents, the diameter and concentration of the Al2O3 on the surface morphology were investigated. Porous fibers and porous microspheres were prepared by regulating the ratio of the solvents from the phase separation and breath figure methods. The dynamic behavior of the water droplet with the constant volume impacting on the electrospinning films were reported. The morphology evolution, restitution coefficient, the change of energy of the water droplets are examined. The droplet bounces several times on the superhydrophobic surface, while the droplet remains pinned and does not rebound when the contact angles was lower than 150°. On the other hand, the water droplets were splashed on the Al2O3 based electrospinning films. Finally, the mechanical properties of the electrospinning films were investigated. [ABSTRACT FROM AUTHOR]

The impact of a drop on a solid surface is an important phenomenon that has various implications and applications. However, the multiphase nature of this phenomenon causes complications in the prediction of its morphological evolution, especially when the drop splashes. While most machine-learning-based drop-impact studies have centred around physical parameters, this study used a computer-vision strategy by training an encoder–decoder to predict the drop morphologies using image data. Herein, we show that this trained encoder–decoder is able to successfully generate videos that show the morphologies of splashing and non-splashing drops. Remarkably, in each frame of these generated videos, the spreading diameter of the drop was found to be in good agreement with that of the actual videos. Moreover, there was also a high accuracy in splashing/non-splashing prediction. These findings demonstrate the ability of the trained encoder–decoder to generate videos that can accurately represent the drop morphologies. This approach provides a faster and cheaper alternative to experimental and numerical studies.

Droplet splashing phenomena are observed experimentally on the well-designed hydrophobic micro and micro-/nano-textured surfaces. The critical Weber numbers (Wecr) for splashing are investigated by considering the geometrical surface conditions. The splashing was facilitated with large micropillar spacing and diameter and suppressed with small ones. Large pillar spacing and diameter enabled easy penetration of liquid by reduced capillary force and increased the outlet of airflow. This air-liquid velocity difference creates instability at the edge of the spreading droplet, thereby generating splashing based on the Kelvin-Helmholtz instability mechanism. Besides, earlier splashing was observed on micro/nano textures than on microtextured surfaces. Since the impacting droplet could not penetrate the nanopillars due to higher capillary pressure and slip boundary condition formation, it reduces airflow friction. Hence an increase in the air-liquid velocity ratio renders splashing. [ABSTRACT FROM AUTHOR]

The present experiment was undertaken to study the effect of misting and splashing during hot-dry and hothumid months in lactating Sahiwal cattle. The study was conducted during May, June (hot-dry) and July (hothumid) with monthly average temperature-humidity index (THI) of 79.88, 80.57 and 85.36, respectively. Eighteen lactating cattle were selected on the basis of days in milk, milk yield, and parity and then divided into three groups: control (no cooling), cooling by misting and cooling by splashing. Milk production was not affected by hot-dry and hot-humid heat stress in Sahiwal cattle. RT and RR were significantly lower in misting and splashing group as compared to control during hot-dry period. The heat stress-induced leucocytosis, lymphocytopenia and neutrophilia were significantly ameliorated by both misting and splashing during the study period. Heat stress-induced alterations in serum creatinine, sodium and ROS concentration were significantly mitigated by misting in hot-humid climate. The prolactin level significantly decreased in animals by misting during the study period. The results suggested that misting was more efficient than splashing as a cooling strategy in hot dry condition while splashing was more effective in hot-humid condition and mitigated the heat stress-induced alterations in different welfare parameters but could not fully nullify it. However, the resultant stress was not sufficient enough to decrease the milk yield in Sahiwal cattle. It may also be concluded that the Sahiwal cattle have high heat tolerance and could sustain production even in a hot-dry and hot-humid environment.

A recently developed conservative level set model, coupled with the Navier-Stokes equations, was invoked to simulate non-spherical droplet impact in three dimensions. The advection term in the conservative level set model was tackled using the traditional central difference scheme on a half-staggered grid. The pressure velocity coupling was decoupled using the projection method. The inhouse code was written in Fortran and was run with the aid of the shared memory parallelism, OpenMP. Before conducting extensive simulations, the model was tested on meshes of varied resolutions and validated against experimental works, with satisfyingly qualitative and quantitative agreement obtained. The model was then employed to predict the impact and splashing dynamics of non-spherical droplets, with the focus on the effect of the aspect ratio. An empirical correlation of the maximum spread factor was proposed. Besides, the number of satellite droplets when splashing occurs was in reasonable agreement with a theoretical model.

• The spreading and splashing of the liquid film by inclined jet impingement were studied using high-speed cameras. • A unique liquid film deflection phenomenon is observed due to the boiling of the liquid film. • The splashing characteristics and mechanism of liquid film have been discussed. In this paper, the liquid film formed by inclined jet impingement on the vertical hot wall is investigated by a high-speed camera. The effects of the jet velocity (5.5 m/s ≤ u 0 ≤ 14.6 m/s, 3804 ≤ Re ≤ 10098) and initial wall temperature (25 ℃≤ T 0 ≤ 250 ℃) on the spreading and splashing of the liquid film are explored. Although the jet velocity and initial wall temperature have little effect on the spreading velocity of the liquid film, the wetting front position and liquid film area increase. For T 0 ≥ 150 ℃, a unique liquid film deflection phenomenon is observed due to the boiling of the liquid film, which results in a substantial amount of splashing. Based on the characteristics of the deflection splashing, three modes are categorized, i.e., annular splashing, banded splashing, and non-splashing. The splashing of the liquid film on the hot surface is owing to the rupture of boiling bubbles, the breakup of surface waves, and the liquid splashing in the boiling zone. The splashing rate of the liquid film is measured, and it is found that an increase in T 0 improves the splashing rate significantly, and the splashing rate even exceeds 70 % at T 0 = 250 °C. [ABSTRACT FROM AUTHOR]

The morphology and microstructure of splats impact the comprehensive capability of a new coating methodology called chelate flame spraying (CFS). This study addresses the quantitative characterization of the spread morphologies of flame sprayed Er 2 O 3 splats directly deposited under different spray conditions on aluminum alloy substrates with a mirror finish. The influence of the in-flight particle temperature and velocity, carrier gas type, and carrier gas ratio on the solidification mechanism of molten droplets was investigated. Image analysis methods were employed to identify single splats from the morphology observed with field-emission scanning electron microscopy (FE-SEM). In addition, Er 2 O 3 films were synthesized on an Al–Mg alloy (A5052) substrate using N 2 or O 2 as the carrier gas. When O 2 was used as the carrier gas, 109-μm-thick films were deposited on the A5052 substrate. The cross-sectional porosity of the films was 3.8%. In contrast, films with 101-μm thickness were synthesized on the A5052 substrate when N 2 was used as the carrier gas. The cross-sectional porosity of these films was 13.8%. The results showed that the carrier gas type (N 2) and carrier gas ratio had a significant effect on the flattening behavior of the molten droplets. A spraying method combined with multidimensional modes is proposed to control the morphology of the splats. [ABSTRACT FROM AUTHOR]

To study the potential applications of liquid lithium (Li) as plasma facing material, the third generation of flowing liquid Li (FLiLi) limiter has been designed and successfully tested in EAST tokamak H-mode discharges in the 2018 run campaign. The stability of liquid Li on FLiLi surface, and Li splashing and its effect on the plasma performance are investigated in detail. Li splashing was observed in L-mode and H-mode discharges due to Rayleigh-Taylor (R-T) instability, resulting from electromagnetic forces J→×B→. Li splashing in low-parameter plasma decreased both core and edge electron temperatures, resulting in the degradation of plasma energy confinement and even H-L back transition, however, it almost did not influence plasma confinement performance in high-parameter plasma. These findings indicate that high-parameter plasma has higher tolerance to Li impurities than low-parameter plasma. By contrast, tungsten splashing from the melted layer on the upper divertor was also induced by the R-T instability but generally resulted in plasma disruption, which suggests lower tolerance to tungsten impurities in EAST tokamak.

Featured Application: Nuclear safety, stratified steam explosion. Small-scale experimental studies of melt splashing upon the impact of water are presented here, with a focus on the fluid dynamics and thermal aspects of these interactions. Gravity-accelerated droplets and forced short-duration water jets interacted with liquid Rose's alloy superheated to 100–200 degrees above its melting point. A repeatability study was performed for better-control of the gravity fall of a droplet. The amount of perturbation on the melt surface was obtained from a video recording, and indicated the existence of three principal stages of interaction. The cases using the forced water jet demonstrated the occurrence of a cumulative jet of melt following the collapse of the cavity caused by the water impact. Also, it was shown that numerous small-diameter melt droplets were scattered by the primary impulse, and small-scale micro-eruptions were observed, which generated small but fast melt droplets at the later stages of interaction. [ABSTRACT FROM AUTHOR]

An efficient time-adaptive multigrid algorithm is used to solve a range of normal and oblique droplet impacts on dry surfaces and liquid films using the Depth-Averaged Form (DAF) method of the governing unsteady Navier–Stokes equations. The dynamics of a moving three-phase contact line on dry surfaces is predicted by a precursor film model. The method is validated against a variety of experimental results for droplet impacts, looking at factors such as crown height and diameter, spreading diameter and splashing for a range of Weber, Reynolds and Froude numbers along with liquid film thicknesses and impact angles. It is found that, while being a computationally inexpensive methodology, the DAF method produces accurate predictions of the crown and spreading diameters as well as conditions for splash, however, underpredicts the crown height as the vertical inertia is not included in the model. [ABSTRACT FROM AUTHOR]

When a gas-liquid two-phase jet is discharged from a nozzle, its surface is fairly smooth for a certain distance from the nozzle exit. Then, deformation develops to cause jet breakup eventually. The deformation length that is defined as the length required for the jet deformation to develop is of industrial importance since significant splashing occurs when deformed jet impinges on a solid surface. The present work investigated the deformation length experimentally using air and water as the test fluids. The flow direction was vertical downward, and annular liquid film was formed at the nozzle exit. It was shown that the deformation develops faster with an increase in the gas flow rate. The measured deformation lengths were about 28.5 times the liquid film thickness estimated at the nozzle exit and no noticeable influence of the Weber number was found. [ABSTRACT FROM AUTHOR]

Bath smelting technologies based on top submerged lance (TSL) injection have been widely used for pyrometallurgical metal production and solid waste treatment. In this work, a two-dimensional CFD simulation model of a pilot-scale 300 kg TSL furnace was established and applied to investigate the slag splashing phenomenon caused by submerged gas injection and combustion, with a special focus on the effect of submerged combustion on bubble formation, splash generation, splash distribution and heat transfer in the top space of the TSL furnace. The slag splash amount and distribution, and the temperature distribution characteristics inside the TSL furnace, especially under the influence of submerged combustion, were predicted, and influences of lance immersion depth and total injection gas flowrate on the splash behavior and heat transfer were investigated. As the lance immersion depth increases, more splashes are generated that distribute more evenly in the furnace top space and consequently heat transfer is enhanced. A larger injection gas flowrate generally increases the splash amount but the effect becomes weak when the injection gas flowrate exceeds a certain level, and there exists an appropriate range in injection gas flowrate for achieving the best heat transfer efficiency in TSL furnace.