Drop Spreading Research Articles

Success and failure of the spreading law for large drops of dense granular suspensions

The spreading of large viscous drops of density-matched suspensions of non-Brownian spheres on a smooth solid surface is investigated experimentally at the global drop scale. The focus is on dense suspensions with a solid volume fraction equal to or greater than $40\,\%$ , and for drops larger than the capillary length, i.e. for which the spreading is governed by the balance of gravitational and viscous forces. Our findings indicate that all liquids exhibit a power-law behaviour typical of gravity-driven dynamics, albeit with an effective suspension viscosity that is smaller than the bulk value. When the height of the drop is of the order of the particle size, the power law breaks down as the particles freeze while the contact line continues to advance.

The initial stage of the coalescence of a compound drop in an impact regime

The evolution of the regular fine structure of the colored matter distribution produced, when a freely falling multifluid drop spreads in deep water, is for the first time traced using the techniques of engineering photo and video recording. The flow pattern is studied in the initial stage of the formation of a cavity and a crown during the coalescence of a compound drop, whose core is a drop of alizarin ink solution coated with an oil shell. The distributions of the colored fluid at the cavity bottom and the crown walls include streaky structures, whose formation can be due to the processes of the available potential surface energy (APSE) conversion occurring when the contact surfaces of the merging fluids are eliminated. In the experiments the height of the falling drop was varied. The core position in the compound drop was not checked but was determined by separation conditions. The ink core disintegration into fibers was observable in all the experiments. The areas of the cavity and crown surfaces covered by the colored fluid reached maximum at the central position of the core.

Effect of Cr, Al and Mo additives on the wetting characteristics of molten Ni on (Ti, Zr, Hf, Nb, Ta)C high entropy ceramics

For the first time, the wetting behavior of the (Ti, Zr, Hf, Nb, Ta)C) high entropy carbide ceramics by molten Ni-based alloys was investigated using a sessile drop technique in a vacuum environment. Adding 10wt% of Cr, Mo, or Al into Ni resulted in final contact angles of 14°, 10°, and 14° on the (Ti, Zr, Hf, Nb, Ta)C substrate, respectively. The interaction mechanism between (Ti, Zr, Hf, Nb, Ta)C and Ni-based alloys occurs in two stages: the dissolution and interaction of the elements Ti, Zr, Hf with the alloys and the dissolution of NbC and TaC at the grain boundaries. SEM observations revealed that Cr and Al additives do not interact with carbides, while Mo was dissolved in carbides. Due to the low contact angle, minimal interaction region between alloy and ceramic, and short time of drop spreading, NiAl alloy is proven to be a promising binder for the HEC-based composites.

Dynamic Drop Penetration of Horizontally Oriented Fiber Arrays.

In this experimental study, we combine drop impact into porous media and onto a single fiber to study drop impact into fiber arrays inspired by mammalian fur coats. In our 3D-printed arrays, we vary the packing density, fiber alignment, strand cross-section, and wettability. Drops impact fibers fixed at both ends, penetrating over short periods of time by momentum and laterally spreading throughout the array. Using image analysis, we measure penetration depth and wetted width into the array. Impact Weber number and intrinsic porosity define penetration, retraction, and rebound regimes. On average, at an impact Weber number of ≈80, staggered fibers reduce penetration by 24% in hydrophilic fibers and 34% in hydrophobic fibers, and the penetration reduction percentage is expected to increase with increasing Weber number. Our results indicate that as density grows toward the density of mammalian pelts, penetration will reach a maximum value independent of drop impact velocity, thereby providing an effective rain barrier. Hydrophilicity at the densities we test, 50-150 strands/cm2, aids fiber array resistance to dynamic penetration by impacting drops through the promotion of lateral drop spreading and inhibition of drop fragmentation. Conversely, hydrophobic fibers best resist low-speed wicking. The fraction of a drop that infiltrates hydrophilic and hydrophobic fibers is nearly identical for a fixed Weber number because lateral spreading restricts the penetration depth into hydrophilic fibers but does not restrict mass infiltration. Above a critical Weber number, the entire drop mass penetrates fiber arrays regardless of strand wettability.

Design and Development of Ardiuno Based Seed Sowing Machine

Pulses is one of the important crops. Pulses has a high dietary value due to their high protein content. The pulse crop is primarily farmed for its grains, which are consumed whole or split (dal). Proper and timely planting has a significant impact on seed germination, plant growth, plant population in the field, and, eventually, overall production. In general, pulses are sown by animal/tractor drawn seed drill or manually. Tractor-drawn seed drills are best suited for medium to large farms with a high seed rate. Draft animals are not only growing more expensive, but they are also becoming scarce. More than 75% of Indian farmers are small and marginal farmers who perform all of their operations manually. Manual sowing is a highly labour intensive, tedious, time consuming and not technically suitable. Therefore, a double row ardiuno based battery operated seed sowing machine for pulses seed was developed and tested. During the study, the required physical property of chickpea seed was determined. The developed seed drill was tested for laboratory and field test. The overall size of developed seed sowing machine was 930×600×740 mm. It was operated through 24V (type Lead acid / li-ion) battery. A DC motor of 250 watt 24V was used as power source. Ground wheels have 15 lugs. It sowed seeds in two rows at a time. The overall weight of developed seed drill was 37 kg. In the laboratory test, seed rate, and mechanical damage of the developed seed sowing machine were 63.20 kg/ha, and 1.20% respectively. The overall performance of the developed seed sowing machine was found satisfactory. While in the field, draft of implement 37.19 kgf, missing index 2.46%, depth of seed placement 6.10cm, and draft of implement 14.51 kgf, missing index 3.63%, depth of seed placement 6.20 cm, The field efficiency of the developed seed sowing machine 83% respectively.

Vibration-triggered spreading of nanofluid drops

This study explores the effects of nanoparticles on the dynamics of drop spreading under external vibration, presenting an advance in the understanding of nanofluid behavior on vibrating substrates. This work introduces insights into nanoparticle-mediated drop spreading, offering implications for improving particulate coatings, mini-mixers, and particle segregation technologies. By employing a twofold approach that combines oscillating drop dynamics with internal flow pattern analysis, we find how even small concentrations of hydrophilic or hydrophobized silica nanoparticles inside water sessile droplets significantly alter the spreading process on silanized glass surfaces. Our study allows distinct drop spreading regimes to be identified based on nanoparticle concentration and vibration amplitude, for both hydrophilic and hydrophobized nanoparticles. Through a comprehensive analysis, we demonstrate that the vibration-triggered spreading of nanofluids can lead to a stable and controlled manipulation of complex liquids.

Numerical contact line behavior prediction for drop-wall impact using Basilisk

Drop-wall impact and spray cooling have a wide technical application. There are still fundamental problems associated with wettability and its effect on the drop spreading. Experiments and direct numerical simulations are performed in a wide range of initial drop velocities (0.2–3.6 m/s). The 3D simulation is implemented by solving the incompressible Navier-Stokes equations along with the volume-of-fluid method in the Basilisk software. An adaptive mesh refinement near the interfacial surface provides a cell size of 5 µ m. The effect of the contact angle calculated using the Hoffman function on the minimum drop height and its maximum spreading is explored. The contact angle affects the dynamics of the contact line. Moreover, the mesh cell size and the initial velocity of a water drop before impact define the development of the drop rim instability when compared with experimental results. Experimental and numerical findings are compared to estimate quantitatively numerical model capabilities.

Impact of drops of epoxy resin and hardener, silicone and turpentine oils onto balsa wood and polypropylene substrates

Electrowetting and wettability-driven spreading of liquids on porous and nonporous substrates was investigated using impact of drops of epoxy resin, epoxy hardener, and epoxy resin and hardener, as well as silicone and turpentine oils with oil-soluble aniline dyes onto balsa wood and polypropylene surfaces. The experimental results revealed that the electric field stretched drops of epoxy resin, epoxy hardener, and epoxy resin and hardener after impact on polypropylene substrate in the long-term. The spreading of drops of epoxy resin and turpentine oil with dyes after impact onto porous balsa wood under the action of a 10 kV applied voltage was relatively weak. In addition, the measured footprint areas corresponding to drops of epoxy resin, epoxy hardener, and epoxy resin and hardener demonstrated a significant increase in the wetted areas driven by the applied voltage of 10 kV on polypropylene substrate, whereas on balsa wood, the footprint is practically unaffected by the electric field. Furthermore, it was determined that surface wettability was the main mechanism of spreading of epoxy resin, as well as silicone and turpentine oils with aniline dyes on porous balsa without the electric field applied. On the other hand, insufficient concentration of ions and counterions in silicone oil was responsible for the absence of electrohydrodynamic effects after impact of such drops onto porous balsa substrate subjected to high potentials of 7 and 10 kV. Hence, wettability-driven spreading with imbibition on balsa wood was the only reason for an increase in the wetted area in the case of silicone oil.

Design, Analysis and Fabrication of Manually Operated Seed Sowing Machine

Abstract: Sowing machine should be suitable to all farms, all types of corps, robust construction, also it should be reliable, and this is basic requirement of sowing machine. Manually operated seed sowing machine reduces the efforts of farmers thus increasing the efficiency of planting also reduces the problem encountered in manual planting. Manually operated seed sowing machine can plant different types and different sizes of seeds also can vary the space between two seeds while planting. This increases the planting efficiency and accuracy. The focus of this research work is to design, analysis of plough and fabricate a low-cost Manually Operated Seed Sowing Machine for effective handling of the machine by any farmer or by any untrained worker with simplified design. The components of seed sowing machine were modelled by using Auto CAD 2022. Analysis of plough was performed by using Ansys 2023-student version. The fabricated seed sowing machine perform the various simultaneous operations and saves labour requirement so as labour cost, labour time and also save lots of energy.

Experimental data – driven algorithm to predict muckpile characteristics in jointed overburden bench using unmanned aerial vehicle and AI tools

ABSTRACT In the current investigation, an intriguing method called Firefly-XGBoost was put up to predict and integrate blast muck-pile results notably drop, throw, and lateral spread, which are instrumental in regulating and remedying the loading problems by loader as well as deceiving factors in type of loader selection. As a result, the particle swarm optimisation (PSO) algorithm and the firefly algorithm were relied on to shore up the efficacy of the XG Boost conventional model. A total of 164 blast experiments were executed in two different mines and the data collected from these trials data were used to train the model. This data includes specific features such as joints spanning height (JSH) as well as other blast characteristics such as the number of joint sets, decking length, total quantity of explosives, stemming length, decking length and firing pattern. The Firefly-XG Boost algorithm yielded better outcomes in terms of RMSE and R 2 values when compared to the XG Boost, and PSO-XG Boost algorithms. The developed model was found to be suitable in predicting muck-pile parameters for practical application.

MANUAL SEED SOWING MACHINE

MANUAL SEED SOWING MACHINE

Musculoskeletal Disorders Among The Seed Sower Workers - A Review

Musculoskeletal Disorders Among The Seed Sower Workers - A Review

The Effect of Three Depths of Mechanical Seed Drill (Gaspardo SC-250) on the Performance of Vicia Faba L. Bean for Yield Characteristics and Components

Current study was conducted on a farm in two sites: the center of Kirkuk Governorate and Hawija District, during the 2022–2023 agricultural season. It focused on two factors: the seeding depths of the Gaspardo SC-250 machine (at 2, 3, and 6 cm) and three varieties (local, Yildiz, and Aquadulce). The land was divided according to a randomized complete block design (RCBD) according to a split-plot system with three replicates. The study allocated the sowing depth factor to the main panels and the variety factor to the secondary panels. The findings showed a notable improvement in yield characteristics and components when sowing depths were increased at both sites. It was observed that the total yield of dry seeds was significantly influenced by sowing depths at both sites, with D3 showing superior results, producing 2074.91 kg/ha and 7854.71 kg/ha, respectively. We observed that the Aquadulce variety had the highest yield rate, producing 5503.64 kg/ha and 7441.37 kg/ha, respectively. There was a significant impact of sowing depths and varieties on this trait at both sites. Specifically, at the Kirkuk site, the Aquadulce variety had the highest yield at depth D1, with 8413.83 kg/ha. At the Hawija site, the Aquadulce variety outperformed the other varieties at depth D3, yielding 9863.83 kg/ha. This superior performance was attributed to the quality of its components, resulting in a significant increase in the final yield.

Drops on Polymer Brushes: Advances in Thin-Film Modeling of Adaptive Substrates.

We briefly review recent advances in the hydrodynamic modeling of the dynamics of droplets on adaptive substrates, in particular, solids that are covered by polymer brushes. Thereby, the focus is on long-wave and full-curvature variants of mesoscopic hydrodynamic models in gradient dynamics form. After introducing the approach for films/drops of nonvolatile simple liquids on a rigid smooth solid substrate, it is first expanded to an arbitrary number of coupled degrees of freedom before considering the specific case of drops of volatile liquids on brush-covered solids. After presenting the model, its usage is illustrated by briefly considering the natural and forced spreading of drops of nonvolatile liquids on a horizontal brush-covered substrate, stick-slip motion of advancing contact lines as well as drops sliding down a brush-covered incline. Finally, volatile liquids are also considered.

Nanofluid Drop Impact on Heated Surfaces.

We experimentally elucidate the impact dynamics of ethylene glycol (EG) droplets laden with both hydrophilic and hydrophobic SiO2 nanoparticles (NPs) onto a flat heated surface in non-boiling, boiling, and Leidenfrost regimes. We use seven nanofluid concentrations (Cp), ranging from 0.89 to 64.3 wt %, and control the surface temperature (Ts) between 100 and 400 °C, while the nanofluid droplet's impact velocity is constant at 0.22 ± 0.02 m/s. Phase diagrams of impact outcomes are established to illustrate the effect of the additive nanoparticles on the droplets' impact dynamics, revealing that nanoparticles modify droplet impact behaviors differently in each regime. In the non-boiling regime, the droplet spreading profile remains unaffected by nanoparticles up to Cp < 11.9 wt % before reaching the maximum spreading diameter (βmax). For nanofluid drops with higher nanofluid concentration, the increasing viscosity with concentration is likely to be the primary factor that affects the droplets' spreading profile in the non-boiling regime Ts ≲ Tsat ≈ 200 °C, as the saturation temperature. In the boiling regime 200 °C < Ts ≲ 350 °C, a small amount of nanoparticle addition (Cp = 0.89 wt %) promotes atomization regardless of nanoparticle wettability. Finally, manifested in a complete rebound due to an intervening vapor layer, the Leidenfrost temperature (TL) of the nanofluid droplets is affected by both nanofluid concentration and nanoparticles' wettability. The nanofluid droplets' TL increases with higher nanofluid concentration; moreover, this Leidenfrost temperature increment is more significant for EG droplets laden with hydrophobic nanoparticles. Our results quantitatively reveal the significant influence of nanoparticle concentrations and wettability on drop spreading, impact outcome, and Leidenfrost temperature on heat surfaces, potentially benefiting applications in coating, spraying, and cooling.

Performance Evaluation of Manual Seeder Machine for Precision Farming

Proper placement of seeds in the field is the most important operation to obtain an optimum yield of the crop. In India, about 75% of the landholders are small and have marginal land-holding capacity. Considering the limitations due to costly seed, the traditional method of manual dibbling, labor shortage, and small marginal land holding pattern there is a need for small manual planters for small and marginal landholders. Cotton, the white gold, is the king of textile, fibers and it is an important worldwide cash crop. The sowing of cotton is labor intensive as its planting requires 3-4 man-days/ha. Because of the above, the manual seeder was tested in the laboratory as well as in the field as per IS code: 6316-1993 with specific objectives. Laboratory analysis of manual seeder as seed rate (2.85 kg/ha and 2.88 kg/ha), seed damage (7.84% and 7.74%), and seed uniformity (62 cm and 64 cm) of cotton and castor crop respectively. Field analysis of manual seeder as coefficient of uniformity (91.63% and 93.23%), depth of seed placement (5.7 cm and 5.9 cm), speed of operation (1.82 km/h 1.84 km/h), theoretical field capacity (0.93 ha/h and 0.93 ha/h), effective field capacity (0.166 ha/h 0.171 ha/h), field efficiency (86.01% and 88.60%), draft (9.54 kgf and 10.46 kgf), energy consumption (10.93 MJ/ha and 10.04 MJ/ha) and cost of operation (440 Rs/ha and 445 Rs/ha) of cotton and castor crop respectively.

A comparative study on the speed-up dynamics of drop spreading on floating and glass-supported polystyrene thin films

The enhanced spreading of a 2D drop on a stiff and free-standing elastic thin film theoretically investigated by Shanahan (Rev. Phys. Appl. 1988, 23, 1031–1037) has not been studied and verified experimentally. To shed a light on this interesting problem, herein, we perform comparison studies on the spreading behavior of a silicone oil drop on stiff polystyrene thin films supported by two different substrates: glass vs. water. Scaling analysis on the time evolution of the contact radius for the drop spreading on the films of varied thickness (∼40 nm to ∼600 nm) reveals the difference on the dynamics for the drop spreading on glass-supported and floating films. Upon fitting the spreading data by using the spreading model developed by de Ruijter et al. (Langmuir 1999, 15, 2209–2216), we are able to identify the speed-up effect for the drop spreading on water supported floating films, which progressively decreases with film thickness and diminishes when the thickness is greater than ∼200 nm. The elastic driving force that is responsible for the speed-up of the drop spreading on the floating film is evaluated empirically, which is found to decay exponentially with contact radius of the drop. The pre-factor and the decay length of the decay function are determined by film thickness and drop volume, resepctively. Our findings expect to facilitate developing new theories with practical relevance on the spreading dynamics of a liquid drop on elastic films.

Water drops on nanofiber-coated substrates: Influence of wall temperature and coating thickness on hydrodynamics and wall heat flux distribution

Heat and mass transport during drop impact or a gentle deposition onto a heated substrate depends on the surface chemistry, morphology, thermal and mechanical properties of the substrate, as well as the substrate temperature. In particular, if a substrate is coated with a porous layer of a wettable material, the drop spreading is accompanied by the imbibition of a liquid into the layer. The wetted area is significantly enhanced in comparison with the area which can be covered by a drop spreading over a bare substrate. As a result, the liquid evaporation rate increases and the evaporation time decreases. Understanding the interaction between the liquid spreading, imbibition and evaporation is important, both for enhancement of heat transfer in cooling applications and for functionalizing of porous media. In our experimental studies, a disk of infrared-transparent calcium fluoride is used as the base substrate. The disk is coated with a submicrometer layer of black chromium nitride and an electrically conductive chromium layer, used for heating of the substrate by electrical current. Nanofiber coating layers are applied on top of the chromium layer using electrospinning. The dynamics of drop spreading is captured by a high-speed camera in a side view, the imbibition is observed with a top view camera, and the temperature distribution at the substrate-coating interface is captured by an infrared camera. Based on the transient temperature field, corresponding heat flux distributions are determined. For the detailed analysis of the interplay between hydrodynamics and heat transfer, the nanofiber coating thickness and substrate temperature have been varied. It has been found that the drop drying time and maximal imbibed area depend non-monotonously on the coating thickness. Changing the initial wall temperature leads to qualitatively different distribution of the heat flux at the substrate surface.

Comparison of pneumatic sowing machines by the number of seeds in the slots of the discs and the distance between the slots

This article compares the pneumatic seeders currently in use. The comparison results provide the following indicators specifying the number of seedlings in the clusters, the distance between the clusters, the width of the clusters and the length of the clusters. Based on the results obtained from 3 sowing machines selected for clustering sowing of seeds, it was determined that it is advisable to improve the sowing disc in order to improve it so that the indicators of the sowing machine in 3 variants exceed the indicators of other devices.

The Main Directions of Improvement of Sowing Disks of Units for Joint Sowing of Two Crops

This article describes the design of an experimental sowing disk for joint sowing of corn and sorghum seeds. The results of laboratory studies are presented and the need to improve the sowing disk and its individual elements is justified. A patent search for sowing machines and sowing disks was carried out in order to analyze and further synthesize the best solutions for the development of new designs of a sowing machine and a sowing disk for joint crops. The necessity of conducting research on further improvement of the disk elements in order to increase its reliability is substantiated.